Treatment with dapagliflozin increases FGF-21 gene expression and reduces triglycerides content in myocardial tissue of genetically obese mice.

BACKGROUND: The association between obesity and some cardiovascular complications such as heart failure (HF) is well established, and drugs affecting adiposity are supposed to be promising treatments for these conditions. The sodium-glucose cotransporter-2 inhibitors (SGLT2i) are antidiabetic drugs showing benefits in patients with HF, despite the underlying mechanisms have not been completely understood yet. SGLT2i are supposed to promote systemic effects, such as triglycerides mobilization, through the enhancement of fibroblast growth factor-21 (FGF-21) activity. So, in this study, we evaluated the effects of dapagliflozin treatment on FGF-21 and related receptors (FGF-Rs) gene expression and on lipid content in myocardial tissue in an animal model of genetically induced obesity to unravel possible metabolic mechanisms accounting for the cardioprotection of SGLT2i. METHODS: Six-week-old C57BL/6J wild-type mice and B6.V-LEP (ob/ob) mice were randomly assigned to the control or treatment group (14 animals/group). Treatment was based on the administration of dapagliflozin 0.15 mg/kg/day for 4 weeks. The gene expression of FGF-21 and related receptors (FGF-R1, FGF-R3, FGF-R4, and ß-klotho co-receptor) was assessed at baseline and after treatment by real-time PCR. Similarly, cardiac triglycerides concentration was measured in the control group and treated animals. RESULTS: At baseline, FGF-21 mRNA expression in the heart did not differ between lean and obese ob/ob mice. Dapagliflozin administration significantly increased heart FGF-21 gene expression, but only in ob/ob mice (p < 0.005). Consistently, when measuring the amount of triglycerides in the cardiac tissue, SGLT2i treatment reduced the lipid content in obese ob/ob mice, while no significant effects were observed in treated lean animals (p < 0.001). The overall expression of the FGF-21 receptors was only minimally affected by dapagliflozin treatment both in obese ob/ob mice and in lean controls. CONCLUSIONS: Dapagliflozin administration increases FGF-21gene expression and reduces triglyceride content in myocardial tissue of ob/ob mice, while no significant effect was observed in lean controls. These results might help understand the cardiometabolic effects of SGLT2i inducing increased FGF-21 synthesis while reducing lipid content in cardiomyocytes as a possible expression of the switch to different energy substrates. This mechanism could represent a potential target of SGLT2i in obesity-related heart diseases.

The ideal blood pressure target to prevent cardiovascular disease in type 2 diabetes: a neutral viewpoint.

Type 2 diabetes mellitus (T2DM) and essential hypertension are often associated, and retrospective data analyses suggest an association between lower blood pressure (BP) values and lower cardiovascular (CV) risk in patients with T2DM. However, the most recent intervention trials fail to demonstrate a further CV risk reduction, for BP levels <130/80 mm Hg, when compared to levels <140/90 mm Hg. Moreover, a J-shaped, rather than a linear, relationship of BP reduction with incident CV events has been strongly suggested. We here debate the main available evidences for and against the concept of 'the lower the better', in the light of the main intervention trials and meta-analyses, with a particular emphasis on the targets to be pursued in elderly patients. Finally, the most recent guidelines of the scientific societies are critically discussed.

A prediction model to assess the risk of egfr loss in patients with type 2 diabetes and preserved kidney function: The amd annals initiative.

OBJECTIVE: To develop and validate a model for predicting 5-year eGFR-loss in type 2 diabetes mellitus (T2DM) patients with preserved renal function at baseline. RESEARCH DESIGN AND METHODS: A cohort of 504.532 T2DM outpatients participating to the Medical Associations of Diabetologists (AMD) Annals Initiative was splitted into the Learning and Validation cohorts, in which the predictive model was respectively developed and validated. A multivariate Cox proportional hazard regression model including all baseline characteristics was performed to identify predictors of eGFR-loss. A weight derived from regression coefficients was assigned to each variable and the overall sum of weights determined the 0 to 8-risk score. RESULTS: A set of demographic, clinical and laboratory parameters entered the final model. The eGFR-loss score showed a good performance in the Validation cohort. Increasing score values progressively identified a higher risk of GFR loss: a score ≥ 8 was associated with a HR of 13.48 (12.96-14.01) in the Learning and a HR of 13.45 (12.93-13.99) in the Validation cohort. The 5 years-probability of developing the study outcome was 55.9% higher in subjects with a score ≥ 8. CONCLUSIONS: In the large AMD Annals Initiative cohort, we developed and validated an eGFR-loss prediction model to identify T2DM patients at risk of developing clinically meaningful renal complications within a 5-years time frame.

A consensus statement for the clinical use of the renal sodium-glucose co-transporter-2 inhibitor dapagliflozin in patients with type 2 diabetes mellitus.

INTRODUCTION: The present review developed a clinical consensus based on a Delphi method on Dapagliflozin, a selective inhibitor of the renal sodium-glucose co-transporter-2 (SGLT2-I) in the treatment of patients with Type 2 diabetes mellitus. Areas covered: Panel members, using a 5-point scale, were asked to rate 9 statements on pharmakodinamic, mode of action on glycaemic and extra-glycaemic effects, and safety of dapaglifozin, Members also aimed to identify the patient most susceptible to the treatment with dapagliflozin . Expert commentary: Dapagliflozin is effective in lowering the plasma glucose concentration with a good safety profile. Dapagliflozin can be utilized in combination with all other antihyperglycaemic agents at all stages of the disease: however, a reduced GFR limits its efficacy. As for the other drugs of the class, Dapagliflozin positively modifies other risk factors for CV disease: these effects will be tested in the so far largest cardiovascular outcome trial for the SGLT2 inhibitors so far, the DECLARE trial, which will communicate whether this class of drugs will be disease-modifier in patients with type 2 diabetes also in primary prevention.

The need for early predictors of diabetic nephropathy risk: is albumin excretion rate sufficient?

Initial studies showing an approximately 80% rate of progression from microalbuminuria (MA) to proteinuria in type 1 diabetic patients led to the broad acceptance of MA as a useful clinical predictor of increased diabetic nephropathy (DN) risk. Some MA patients, however, have quite advanced renal structural changes, and MA may, in these cases, be a marker rather than a predictor of DN. More recent studies have observed only about a 30-45% risk of progression of MA to proteinuria over 10 years, while about 30% of type 1 diabetic patients with MA became normoalbuminuric and the rest remained microalbuminuric. The finding that some MA patients have only mild diabetic renal lesions is consistent with the lower than originally estimated risk of progression from MA to proteinuria and with the notion that some MA patients revert to normoalbuminuria. To increase the complexity of the scenario, some normoalbuminuric long-standing type 1 diabetic patients have well-established DN lesions and approximately 40% of all patients destined to progress to proteinuria are normoalbuminuric at initial screening, despite many years of diabetes. A similar picture is emerging in type 2 diabetic patients, although fewer studies have been conducted. Thus, the predictive precision for MA to progress to overt nephropathy over the subsequent decade or so is considerably less than originally described. It is unclear whether this is due to changes in the natural history of DN resulting from improved glycemia and blood pressure control, or whether there were overestimates of risk in the original studies due to the small sample sizes, post hoc analyses, and variable MA definitions. Albumin excretion rate (AER) remains the best available noninvasive predictor of DN risk and should be regularly measured according to established guidelines. However, AER may be unable to define patients who are safe from or at risk of DN with an accuracy that is adequate for optimal clinical decision making or for the design of certain clinical trials. Investigations into new risk markers or into the combined use of several currently available predictive parameters are needed.

Glomerular structure in nonproteinuric IDDM patients with various levels of albuminuria.

Although microalbuminuria is known to foretell the later development of overt proteinuria in patients with insulin-dependent diabetes mellitus (IDDM), different investigators have reported different levels of albuminuria as being predictive. However, whether different levels of albuminuria reflect differences in glomerular structure is not well known. In this study, we divided a cohort of 66 nonproteinuric long-standing (duration 20 +/- 7 years) IDDM patients, who had both renal functional and structural studies performed, into four groups according to their urinary albumin excretion rate (AER). The several different levels of microalbuminuria previously reported to be predictive served to demarcate these groups: group I, AER < or = 22 mg/24 h (upper limit for normal in our laboratory) (33 patients); group II, AER 23-45 mg/24 h (11 patients); group III, AER 46-100 mg/24 h (13 patients); and group IV, AER 101-220 mg/24 h (9 patients). Creatinine clearance was similar in groups I, II, and III but was lower in group IV. Systemic hypertension was present in five patients in group I, one in group II, seven in group III, and five in group IV. Mean values for glomerular basement membrane (GBM) width and volume fraction of the mesangium [Vv(mes/glom)] were greater in all groups than in a group of 52 age-matched normal kidney donors (P < 0.0001). Also, filtration surface density [Sv(PGBM)], inversely related to Vv(mes/glom) (r = 0.61, P < 0.0001), was reduced in all diabetic groups compared with the normal group (P < 0.0001). Structural measures were identical in group I and II.(ABSTRACT TRUNCATED AT 250 WORDS)

Is diabetic nephropathy inherited? Studies of glomerular structure in type 1 diabetic sibling pairs.

Only a minority of patients with type 1 diabetes develop diabetic nephropathy (DN). Poor glycemic control cannot fully explain DN risk, and family studies suggest genetic susceptibility factors. To understand familial DN concordance, we evaluated glomerular structure in families with type 1 diabetic sibling pairs. Kidney function and biopsy studies were performed in 21 probands (P) (first to develop diabetes) and 21 siblings (S) (second to develop diabetes), most with normal urinary albumin excretion rates (UAER). Glomerular structure was measured by morphometry. Intrafamilial correlation was estimated by one-way random-effects ANOVA and by mixed-effects ANOVA, adjusting for age and duration of diabetes. Diabetes duration was, by definition, longer in P than in S, while age and sex were similar. HbA1c over 5 years and blood pressure were not different in P and S and were without familial effect. UAER was greater in P than in S (P < 0.05), with strong familial effect (P = 0.03). A strong concordance among siblings for mesangial fractional volume (P < or = 0.01) remained significant after adjustment for diabetes duration and age (P = 0.04). Results were similar for mesangial cell (P = 0.01; adjusted P = 0.04) and mesangial matrix fractional volumes (P < 0.01; adjusted P = 0.06). There was also clustering of the patterns of glomerular lesions. For example, if P had relatively marked glomerular basement membrane thickening compared with mesangial matrix expansion, S had a similar pattern (chi2, P < 0.025). Strong concordance in severity and patterns of glomerular lesions in type 1 diabetic siblings, despite lack of concordance in glycemia, supports an important role for genetic factors in DN risk.

Metabolic control of kidney hemodynamics in normal and insulin-dependent diabetic subjects. Effects of acetoacetic, lactic, and acetic acids.

Diabetes mellitus is associated with important changes in renal hemodynamics. The purpose of this study was to determine whether an increase in blood concentration patterns of ketone bodies and lactic acid, organic acids often elevated in poorly controlled insulin-dependent diabetes mellitus (IDDM), could contribute to increase glomerular filtration rate (GFR) and renal plasma flow (RPF) regardless of changes in circulating levels of glucose and insulin. Six IDDM patients and six normal subjects were given a saline infusion (15 mumol.min-1.kg-1) for 2 h, an acetoacetic acid infusion (15 mumol.min-1.kg-1) for another 2 h, and then a saline infusion after an overnight fast during euglycemic insulin-glucose clamp. Acetoacetic acid infusion resulted in an increase of blood ketone bodies in the range of 0.7-1.5 mM from a basal value of 0.1-0.3 mM. GFR was 125 +/- 16 and 136 +/- 17 ml.min-1.1.73 m-2 in normal and IDDM subjects, respectively, during baseline saline infusion and 138 +/- 21 (P less than .01 vs. basal level) and 158 +/- 15 ml.min-1.1.73 m-2 (P less than .001 vs. basal level) during acetoacetic acid infusion. During the last saline infusion, renal hemodynamic patterns decreased again to baseline levels. Another six IDDM patients and six normal subjects were given saline, lactic acid, and saline infusions at the same rates of infusion after an overnight fast during euglycemic insulin-glucose clamp. Lactic acid concentration increased from approximately 0.5-0.8 to 1.0-1.5 mM in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of insulin and atrial natriuretic peptide in sodium retention in insulin-treated IDDM patients during isotonic volume expansion.

Because insulin shows an antinatriuretic effect in healthy humans, insulin therapy resulting in circulating hyperinsulinemia may lead to sodium retention and in turn to hypertension in individuals with insulin-dependent diabetes mellitus (IDDM). Moreover, it has been proved that atrial natriuretic peptide (ANP) plays a major role in modulating natriuresis in humans. This study investigated the relationship between insulin and ANP in modulating sodium metabolism in normotensive and hypertensive IDDM subjects compared with control groups of normotensive and hypertensive nondiabetic subjects. IDDM normotensive and hypertensive subjects had mean +/- SE duration of IDDM of 7 +/- 2 and 8 +/- 2 yr, respectively, and had no clinical features of diabetic nephropathy. All subjects received a saline infusion (2 mmol.kg-1.90 min-1) during euglycemia. IDDM normotensive and hypertensive subjects received a subcutaneous insulin infusion (15 mU.kg-1.h-1), resulting in twofold higher plasma free-insulin levels (16 +/- 2 and 19 +/- 3 microU/ml, respectively) than in nondiabetic normotensive and hypertensive subjects (7 +/- 2 and 8 +/- 2 microU/ml, respectively). During saline challenge, sodium excretion increased by 22 +/- 4% in normotensive and 49 +/- 9% in hypertensive nondiabetic subjects but by only 11 +/- 0.4% in normotensive (P less than 0.01) and 8 +/- 2% in hypertensive (P less than 0.01) IDDM subjects. The impaired natriuretic response to saline challenge was mainly due to greater rates of sodium reabsorption by kidney proximal tubules in IDDM than nondiabetic subjects. At baseline, plasma ANP concentrations were significantly higher in both IDDM groups than in control groups (normotensive IDDM and control subjects: 38 +/- 4 and 19 +/- 2 pg/ml, respectively, P less than 0.01; hypertensive IDDM and control subjects: 45 +/- 6 and 27 +/- 4 pg/ml, respectively, P less than 0.05). After saline challenge, ANP concentrations rose to 39 +/- 4 pg/ml in normotensive and 49 +/- 5 pg/ml in hypertensive control subjects, whereas no significant change above baseline value was seen in IDDM subjects. Both IDDM groups showed a 10-12% greater exchangeable Na+ pool than control subjects regardless of the presence of hypertension. Subcutaneous insulin infusion, resulting in circulating plasma free-insulin levels in normotensive control subjects comparable to those in IDDM patients, inhibited natriuresis, increased proximal tubule sodium reabsorption at the level of the kidney, and inhibited an adequate ANP stimulation by saline challenge. We conclude that hyperinsulinemia leads to increased proximal tubule sodium reabsorption and impaired ANP response during saline administration. Both mechanisms account for sodium retention in normotensive and hypertensive IDDM patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Role of atrial natriuretic peptide in the pathogenesis of sodium retention in IDDM with and without glomerular hyperfiltration.

The pathogenetic determinants of sodium retention in IDDM are not fully understood. The aim of this study was to elucidate the action of ANP in 11 IDDM patients with high GFR (greater than or equal to 135 ml.min-1 x 1.73 m-2), referred to here as HF patients; in 10 IDDM patients with normal GFR (greater than 90 and less than 135 ml.min-1 x 1.73 m-2), referred to here as NF patients; and 12 control subjects, here called C subjects, at baseline and during saline infusion administered on the basis of either body weight (2 mmol.kg-1 x 60 min-1; Saline 1) or of ECV (12 mM.ECVL-1 x 90 min-1; Saline 2) during euglycemic insulin-glucose clamp. C subjects and both HF and NF IDDM patients received a second Saline 1 infusion accompanied by ANP infusion (0.02 microgram.kg-1.min-1) at euglycemic levels. HF and NF patients were studied again after 3 mo of treatment with (10 mg/day). Quinapril (CI 906, Malesci, Florence, Italy), an ACE inhibitor without sulfhydryl group. At baseline, both HF and NF IDDM patients had higher plasma ANP concentrations than C subjects (HF, 36 +/- 4, P less than 0.01 and NF, 34 +/- 3, P less than 0.01 vs. C, 19 +/- 3 pg/ml). Plasma ANP and natriuretic response to isotonic volume expansion was impaired both in HF (44 +/- 8 pg/ml, NS vs. base) and NF (40 +/- 7 pg/ml, NS vs. base) compared with C (41 +/- 4 pg/ml, P less than 0.01 vs. base) during Saline 1. On the contrary, plasma ANP response to Saline 2 was similar in HF and NF patients and C subjects, but IDDM patients had still lower urinary sodium excretion rates. The simultaneous administration of ANP and Saline 1 resulted in comparable plasma ANP plateaus in C subjects and HF and NF patients. However, urinary sodium excretion rate was significantly lower in HF and NF patients than in C subjects: HF, 267 +/- 64, P less than 0.01 and NF, 281 +/- 42, P less than 0.01 vs. C, 424 +/- 39 mumol.min-1 x 1.73 m-2. During simultaneous administration of ANP and Saline 1, GFR and FF increased in C subjects, but not in HF and NF patients. HF and NF patients had higher urinary vasodilatory prostanoid excretion rates than C subjects at baseline. Saline infusion did not change urinary excretion rate of prostanoids either in C subjects or IDDM patients (both NF and HF).(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of cilazapril and amlodipine on kidney function in hypertensive NIDDM patients.

Contrasting information has been reported concerning the course of renal function in NIDDM with hypertension alone or in association with renal damage. The aim of the present study was to elucidate the course of the glomerular filtration rate (GFR) in hypertensive NIDDM patients during antihypertensive therapy. Furthermore, we compared the effects of ACE inhibitors (cilazapril, Inibace, Roche, Milan, Italy) and Ca(2+)-channel blockers (amlodipine, Norvasc, Pfizer, Rome, Italy). Of the hypertensive NIDDM patients attending the outpatient's clinic of the internal medicine departments of the University of Padova and Sassari, 44 participated in the present study. Of these patients, 26 were normoalbuminuric and 18 microalbuminuric. They were randomly treated with either cilazapril or amlodipine. The target of antihypertensive treatment was a value < 140 mmHg for systolic and 85 mmHg for diastolic blood pressure (BP). Microalbuminuria was defined as an albumin excretion rate (AER) between 20 and 200 micrograms/min. GFR was measured by plasma clearance of 51Cr-labeled EDTA at baseline and every 6-12 months during a 3-year follow-up interval. A significant decrease was observed in the values of GFR, AER, and systolic and diastolic BP in normoalbuminuric and microalbuminuric patients during antihypertensive therapy. The GFR fall in the overall population of NIDDM patients was significantly and inversely related to the decrease of mean BP (diastolic + 1/3 pulse pressure) (r = -0.80, P < 0.0001) but not to that of HbA1c, triglycerides, and BMI. The GFR decline (mean +/- SE) per year in the normoalbuminuric patient was 2.03 +/- 0.66 ml.min-1 x 1.73 m-2 (95% CI 0.92-3.17) during cilazapril and 2.01 +/- 0.71 ml.min-1 x 1.73 m-2 (95% CI 0.82-3.11) during amlodipine therapy. The GFR decline per year in the microalbuminuric patient was 2.15 +/- 0.69 ml.min-1 x 1.73 m-2 (95% CI 0.86-3.89) during cilazapril and 2.33 +/- 0.83 ml.min-1 x 1.73 m-2 per year (95% CI 1.03-3.67) during amlodipine therapy. Cilazapril and amlodipine lowered AER to a similar extent in normoalbuminuric and microalbuminuric patients. No significant changes were observed concerning other clinical and biochemical features between the two antihypertensive therapies and particularly HbA1c, BMI, triglycerides, and cholesterol plasma values. These results support the tenet that arterial hypertension plays a pivotal role in contributing to renal damage in NIDDM, even when AER is normal. However, the degree of BP control, with both cilazapril and amlodipine, can successfully delay the slope of GFR decline in hypertensive NIDDM patients with or without incipient nephropathy.

Kidney hemodynamics after ketone body and amino acid infusion in normal and IDDM subjects.

Little information is available on the hemodynamic response (renal reserve) of the diabetic kidney during an acute amino acid infusion, which has been shown to increase glomerular filtration rate (GFR) in normal humans. We recently found that the infusion of ketone bodies is able to raise GFR in both normal subjects and insulin-dependent diabetes mellitus (IDDM) patients. The aim of this study was to evaluate the renal reserve in 15 IDDM patients with a duration of diabetes of greater than 9 yr [8 with albumin excretion rate less than 15 micrograms/min (group 1) and 7 with albumin excretion rate greater than 100 micrograms/min (group 2)] and in 8 normal subjects during amino acid infusion (33 mumol.kg-1.min-1, Travasol 10% wt/vol solution containing 0.154 mM sodium chloride concentration; Travenol, Savage, MD) and during acetoacetic sodium salt (25 mumol.kg-1.min-1) infusion. Blood glucose was clamped at euglycemic levels. The infusion of sodium acetoacetate resulted in a 10- to 15-fold increase in circulating concentrations of ketone bodies, which were similar in magnitude in normal subjects and diabetic patients. The GFR peak increase above baseline after sodium acetoacetate infusion was 28% in normal subjects and 27% in group 1 and 19% in group 2 diabetic patients. The infusion of amino acid solution produced a three- to fivefold increase in plasma concentrations of amino acids in both normal subjects and diabetic patients. The GFR peak increase above baseline after amino acid infusion was significantly lower in diabetic patients (IDDM group 1: 5%, P less than .01; IDDM group 2: 6%, P less than .01) than in normal subjects (38%).(ABSTRACT TRUNCATED AT 250 WORDS)

Course of renal function in type 2 diabetic patients with abnormalities of albumin excretion rate.

Heterogeneity in renal structure has been described in type 2 diabetic patients with both microalbuminuria and proteinuria; in fact, only a subset of type 2 diabetic patients have the typical diabetic glomerulopathy. However, it is currently unknown whether abnormalities in albumin excretion rate (AER) have a different renal prognostic value depending on the underlying renal structure. Aims of this study were: 1) to study the course of renal function in type 2 diabetic patients with altered AER; 2) to evaluate the relationship between the course of glomerular filtration rate (GFR) and renal structure; and 3) to evaluate the relationship between the course of GFR and baseline AER levels, metabolic control, and blood pressure levels during a follow-up period of 4 years. A total of 108 type 2 diabetic patients, 74 with microalbuminuria (MA) and 34 with proteinuria (P), were recruited into a prospective study that encompassed: 1) a baseline kidney biopsy with morphometric measurements of glomerular parameters; 2) intensified antihypertensive treatment for an average 4-year period (blood pressure target <140/90 mmHg); and 3) determinations of GFR at baseline and every 6 months. Mean (+/- SD) GFR significantly decreased from baseline in both MA (-1.3+/-9.4 [95% CI -3.51 to +0.86], P < 0.05) and P (-3.0+/-13.0 ml x min(-1) x 1.73 m(-2) per year [-7.71 to +1.61], P < 0.01). However, the changes in GFR were quite heterogeneous. Thus, on the basis of percent GFR change per year from baseline (delta%GFR), both MA and P patients were defined as progressors or nonprogressors when they were below or above the median, respectively. Baseline parameters of glomerular structure had a strong influence on the course of GFR. Indeed, the odds ratios of being progressors significantly increased across the quartiles of baseline glomerular basement membrane (GBM) width and mesangial fractional volume [Vv(mes/glom)], being 2.71 and 2.85 higher, respectively, in the fourth quartile than in the first quartile (P < 0.01 for both). Conversely, nonprogressors outnumbered progressors in the first quartile of GBM width (odds ratio: 2.14, P < 0.05) and in the first quartile of Vv(mes/glom) (odds ratio: 2.28, P < 0.01). Baseline albumin excretion rate (AER) did not influence delta%GFR; in fact, the number of progressors did not increase across quartiles of baseline AER among either MA or P. Similarly, mean blood pressure levels during follow-up (and intensified antihypertensive therapy) did not affect the course of GFR: the number of progressors and nonprogressors did not change across quartiles of mean blood pressure. In contrast, HbA1c during follow-up had an impact on delta%GFR: the odds ratio for being a progressor increased across quartiles of HbA1c, particularly for the highest quartile (HbA1c >9.0%). In conclusion, the course of renal function is heterogeneous in type 2 diabetic patients with microalbuminuria or proteinuria. In fact, a subset of patients has a rapid decline in GFR over a 4-year follow-up period; these patients have more advanced diabetic glomerulopathy and worse metabolic control than the remaining patients, whose GFR remains stable. These two cohorts are otherwise undistinguishable as regards the degree of AER at baseline and tight blood pressure control. Kidney biopsy has an important prognostic role in these patients. Thus, tight blood pressure control, when not associated with satisfactory glycemic control, is unable to prevent rapid GFR decline in type 2 diabetic patients with typical diabetic glomerulopathy.

Insulin-dependent diabetes mellitus and hypertension.

Contrasting results have been reported regarding the prevalence of hypertension in insulin-dependent diabetes mellitus (IDDM), showing a slightly higher or normal percentage of IDDM patients with elevated blood pressure levels than in the general population. Most of the cross-sectional and prospective studies on the prevalence of hypertension in IDDM show an association between microalbuminuria and elevated blood pressure levels. However, it is not clear whether hypertension is simply secondary to kidney damage or whether hypertension occurs with or even before the development of impaired kidney function. Patients with IDDM have a higher exchangeable body Na+ pool. Na+ retention in IDDM is accounted for by several metabolic and hormonal abnormalities such as hyperglycemia, hyperketonemia, hyperinsulinemia, altered secretion, and resistance to atrial natriuretic peptide. High blood pressure appears to be dependent, at least at some phase, on expansion of extracellular fluid volume as a consequence of defects in the renal secretion of Na+ and water. On the other hand, a tendency toward Na+ retention characterizes all patients with IDDM, whereas hypertension develops only in a subgroup of diabetic patients. One possible explanation for these findings is that a genetic predisposition plays a role in creating susceptibility to hypertension and perhaps to diabetic nephropathy independent of diabetes, even if Na+ retention can further deteriorate this susceptibility to hypertension. With regard to this issue, it has recently been suggested that the risk of kidney disease in patients with IDDM is associated with a genetic predisposition to hypertension. Furthermore, diabetic nephropathy occurs in familial clusters, because diabetic siblings of nephropathic diabetic patients show a higher frequency of diabetic nephropathy than the diabetic siblings of nonnephropathic diabetic patients. One of the possible genetic markers that could be useful to identify the diabetic patients with susceptibility to hypertension and diabetic nephropathy is the Na+(-)Li+ countertransport activity in erythrocytes.

Renal hemodynamics and albumin excretion rate in patients with diabetes secondary to acquired pancreatic disease.

OBJECTIVE--To assess kidney function and AER in patients with PD. RESEARCH DESIGN AND METHODS--Thirty-three patients with PD (age 52 +/- 7 yr, duration of disease 11 +/- 6 yr, BMI 24 +/- 3 kg/m2) and 33 patients with IDDM were matched for sex, BMI, and duration of disease. GFR and RPF were determined by single injection of [51Cr]EDTA and [125I]hippurate. AER was measured by radioimmunoassay in a single timed overnight urine collection. RESULTS--GFR and RPF were, respectively, 113 +/- 35 and 441 +/- 145 ml.min-1.73 m2 in patients with PD and 123 +/- 30 and 549 +/- 94 (P < 0.001) in IDDM. FF was significantly higher in patients with PD (0.26 +/- 0.05 vs. 0.22 +/- 0.03; P < 0.001). Prevalence of hyperfiltration (GFR > 135 ml.min-1.1.73 m2) was similar in both groups (30% in patients with PD vs. 28% in those with IDDM). Geometric mean of urinary AER was 10.4 micrograms/min (range 1-186) in patients with PD and 11.2 (1-198) in IDDM patients. Some 30.3% of patients with PD and 18% of those with IDDM were microalbuminuric (AER > 20 micrograms/min). By multiple regression analysis, AER was significantly related to systolic (P < 0.04) and diastolic blood pressure (P < 0.01) and to BMI (P < 0.03) in patients with PD. Retinopathy was more frequent in microalbuminuric patients with PD than in those without elevated AER. CONCLUSIONS--We suggest that early renal abnormalities occur similarly in patients with PD and IDDM.

Porcine and human insulin absorption from subcutaneous tissues in normal and insulin-dependent diabetic subjects: a deconvolution-based approach.

The mechanisms of sc insulin absorption are not understood, and models for interpreting in vivo data cannot be developed without gross simplification. To overcome this difficulty we developed a new approach which makes use of deconvolution analysis and does not require any model of the sc tissue. In five normal subjects and seven insulin-dependent diabetic (IDDM) patients endogenous insulin secretion was suppressed by means of a hypoglycemic glucose clamp procedure (approximately 2.8 mmol/L) sustained by a continuous insulin infusion (approximately 4 pmol/min.kg). A bolus injection of insulin (5.4 nmol) was administered iv, and plasma insulin concentrations were measured frequently for 2 h to assess iv insulin kinetics. Insulin then was injected sc in the abdominal region, and plasma insulin concentrations were measured for 8 h. Each subject was studied twice, with porcine and semisynthetic human insulin (Actrapid, Novo). The rate of insulin absorption was reconstructed by deconvolution from the plasma concentrations and iv insulin kinetic data. Linearity of the iv insulin kinetics, essential for deconvolution analysis, was confirmed by a dose-response study in the range of the measured concentrations (150-1800 pmol/L). In most instances, a two-compartment model was adequate to describe the iv response. The mean plasma insulin clearance rates were 15.5 +/- 1.9 (+/- SD) mL/min.kg (porcine) and 17.2 +/- 6.0 (human) in normal subjects and 20.7 +/- 8.8 (porcine) and 20.9 +/- 9.1 (human) in the IDDM patients. The rate of appearance of human insulin from sc tissue was faster than that of porcine insulin in both normal and IDDM subjects, but no significant differences were found in bioavailability, which was 55 +/- 12% (+/- SD; porcine) and 61 +/- 34% (human) in the normal subjects, and 84 +/- 28% (porcine) and 86 +/- 23% (human) in the IDDM patients. The rate of absorption and bioavailability were higher in the IDDM patients than in the normal subjects, a difference possibly related to increased sc blood flow in the IDDM patients. No differences were found with regard to glucose requirement values, normalized to plasma insulin concentrations, in agreement with the finding that the bioavailability of the two insulin species was similar.

Sodium-lithium countertransport and cardiorenal abnormalities in essential hypertension.

The rate of red blood cell sodium-lithium countertransport is elevated only in a subgroup of patients with essential hypertension. We have therefore compared renal and cardiac function and morphology in two groups of hypertensive patients with high (n = 23) or normal (n = 22) sodium-lithium countertransport (mean +/- SEM: 0.61 +/- 0.10 versus 0.29 +/- 0.07 mmol/l red blood cells.hr). The two groups were similar in age, sex distribution, body mass index, smoking habit, duration of hypertension, and actual levels of untreated blood pressure. Hypertensive patients with elevated sodium-lithium countertransport activity showed elevated glomerular filtration rate (118 +/- 2 versus 109 +/- 2 ml/min.1.73 m2; p less than 0.001), albumin excretion rate (23 +/- 3 versus 14 +/- 2 micrograms/min; p less than 0.001), larger kidney volume (250 +/- 15 versus 203 +/- 13 ml.1.73 m2; p less than 0.01), lower lithium clearance rate (26.7 +/- 0.3 versus 28.9 +/- 0.3 ml/min.1.73 m2; p less than 0.01), and higher total body exchangeable sodium (2,716 +/- 33 versus 2,485 +/- 41 mmol.1.73 m2; p less than 0.01). Left ventricular mass index (139 +/- 6 versus 119 +/- 6 g/m2; p less than 0.05), relative wall thickness (0.39 +/- 0.05 versus 0.29 +/- 0.04 cm; p less than 0.001), and left posterior wall plus intraventricular septum thickness (2.02 +/- 0.04 versus 1.76 +/- 0.03 cm; p less than 0.05) were also higher in patients with high sodium-lithium countertransport. Hypertensive patients with normal sodium-lithium countertransport had renal and cardiac parameters similar to those of a normotensive control group (n = 21) except for a higher glomerular filtration rate and left ventricular mass index.(ABSTRACT TRUNCATED AT 250 WORDS)

Type I diabetes is characterized by insulin resistance not only with regard to glucose, but also to lipid and amino acid metabolism.

Resistance to the metabolic effects of insulin has been reported with regard to glucose disposal in type I diabetic patients (IDDM) even when they were euglycemic. Our aim was to study glucose, lipid, and amino acid metabolism during glucose clamping at multiple levels of insulin in 10 normal (N) and 6 IDDM patients. Blood glucose was maintained constant (4.7 mmol/liter) at three insulin plateaus (160 min each) [42 +/- 6 (SD) 89 +/- 11, and 1255 +/- 185 microU/ml in N and 36 +/- 4, 80 +/- 13, and 1249 +/- 107 microU/liter in IDDM]. Mean glucose disposal was 34 +/- 11, 69 +/- 10, and 84 +/- 22 mumol kg-1 min-1 in N and 16 +/- 5, 40 +/- 18, and 65 +/- 27 in IDDM, respectively. Baseline concentrations of blood lactate, pyruvate, alanine, and branched chain amino acids were 560 +/- 130, 36 +/- 9, 212 +/- 44, and 451 +/- 19 mumol/liter, in N and 793 +/- 179 (P less than 0.05), 45 +/- 14, 195 +/- 50, and 439 +/- 33 in IDDM, respectively. The maximum percent change of lactate during the euglycemic clamp was +147 +/- 23% in N and +75 +/- 15% (P less than 0.05) in IDDM; that of branched chain amino acids was -61 +/- 5% in N and -48 +/- 7% (P less than 0.01) in IDDM. Baseline concentrations of glycerol, FFA, and adipate were 44 +/- 15, 449 +/- 152, and 8 - 8 mumol/liter in N and 39 +/- 14, 473 +/- 44, and 41 +/- 14 (P less than 0.01) in IDDM. The maximum percent change of glycerol during the euglycemic clamp was -50 +/- 8% in N and -16 +/- 8% (P less than 0.01) in IDDM, that of FFA -98 +/- 3% in N and -70 +/- 4% in IDDM (P less than 0.05). No significant differences were found between N and IDDM with regard to blood concentrations of ketone bodies, citrate, ketoglutarate, and hydroxymethylglutaryl coenzyme A both before and during the euglycemic clamp. The lactate percent increase was significantly correlated to glucose disposal rate (P less than 0.001). The lactate turnover rate increased during the euglycemic clamp and was lower in IDDM than in N. We conclude that during euglycemic-multiple insulin clamp studies the greater lactate increase suggests that the flux of glycolysis is higher in N than in IDDM, tricarboxylic acid concentrations are comparable in N and IDDM, and FFA, glycerol, and branched chain amino acid decreases were less in IDDM than in N, suggesting that IDDM patients are resistant to insulin with regard to lipid and protein metabolism. The higher adipate basal values demonstrate enhanced omega-oxidation in IDDM.

Glomerular filtration rate is increased in man by the infusion of both D,L-3-hydroxybutyric acid and sodium D,L-3-hydroxybutyrate.

A high glomerular filtration rate (GFR) is often found early in insulin-dependent diabetes mellitus (IDDM). It has been suggested that high circulating glucose, glucagon, and GH levels could play a role in this increase in GFR. On the other hand, patients with IDDM in poor metabolic control also have high circulating ketone body levels. This study was undertaken to determine whether exogenous D,L-3-hydroxybutyric acid at two infusion rates (40 and 30 mumol kg-1 min-1) for 180 min altered renal plasma flow (RPF), GFR, and the excretion rate of total protein, beta 2-microglobulin, and albumin in 11 normal (N) subjects and 11 IDDM patients in whom euglycemia was achieved and maintained using the insulin-glucose clamp technique. RPF and GFR were measured by a priming-continuous infusion of [125I]hippurate and [51Cr]EDTA, respectively. The 40 mumol kg-1 min-1 D,L-3-hydroxybutyric acid infusion increased RPF and GFR in both N and IDDM subjects. Mean RPF increased from 588 +/- 78 (+/- SD) to 706 +/- 129 mL min-1 1.73 m-2 in N and from 671 +/- 101 to 781 +/- 99 in IDDM. GFR increased from 121 +/- 11 to 151 +/- 15 ml min-1 1.73 m-2 in N and from 136 +/- 11 to 191 +/- 16 in IDDM. The filtration fraction also was significantly higher in IDDM than in N during the D,L-3-hydroxybutyric acid infusion. The 30 mumol kg-1 min-1 D,L-3-hydroxybutyric acid infusion increased RPF and GFR to a somewhat lesser extent in both groups. D,L-3-hydroxybutyric acid infusions increased the tubular reabsorption rate of ketone bodies and sodium. The increase in tubular sodium reabsorption rate was correlated significantly to that in the tubular ketone body reabsorption rate. A significant decrease in urinary pH was found during the D,L-3-hydroxybutyric acid infusion. D,L-3-Hydroxybutyrate sodium salt (30 mumol kg-1 min-1) also was infused in 5 of the 11 diabetic patients. A similar increase in GFR and RPF occurred. Both total protein and beta 2-microglobulin, but not albumin, excretion rates increased during D,L-3-hydroxybutyric acid (40 mumol kg-1 min-1) infusion in N and IDDM subjects. D,L-3-Hydroxybutyric acid infusion did not change plasma glucagon, GH, or renin activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Polymorphisms of angiotensin-converting enzyme and angiotensinogen genes in type 2 diabetic sibships in relation to albumin excretion rate.

Familial clustering of altered albumin excretion and nephropathy risk has been described in both type 1 and type 2 diabetes; moreover, an association of micro-macroalbuminuria and diabetic retinopathy has been recently reported in a large number of white families with type 2 diabetes. Conflicting reports, mainly comparing affected with unaffected unrelated subjects, have suggested a possible role of some genotypes of the renin-angiotensin system in conferring nephropathy risk in type 2 diabetes. To examine the role of genetic factors in influencing albuminuria in families, we studied the relation of angiotensin-converting enzymes (ACE) and angiotensinogen (AGN) genotypes with albumin excretion rate in a population of affected siblings of type 2 diabetic probands. We determined ACE insertion/deletion polymorphism and two polymorphisms of the AGN gene (T174M and M235T) in 160 families with at least one affected member. Defining proband as the patient with the longest known duration of diabetes, we compared the allelic distribution in diabetic probands with and without altered albumin excretion and in their siblings. Allelic distribution of these polymorphisms was similar in the two groups of probands, as well as in their siblings. Identity-by-State (IBS) analysis showed a link between AGN locus and arterial hypertension in these siblings, which was independent from the degree of renal involvement. Thus, our findings suggest that in white families with type 2 diabetes, there is no linkage between the degree of albumin excretion and ACE and AGN polymorphisms, whereas the latter is related to arterial hypertension, as previously found in patients without diabetes but with essential hypertension.