Physician experts in diabetes are natural team leaders for managing diabetic patients with foot complications. A position statement from the Italian diabetic foot study group.

Diabetic foot syndrome (DFS) is a complex disease. The best outcomes are reported with the multi-disciplinary team (MDT) approach, where each member works collaboratively according to his/her expertise. However, which health provider should act as the team leader (TL) has not been determined. The TL should be familiar with the management of diabetes, related complications and comorbidities. He/she should be able to diagnose and manage foot infections, including prompt surgical treatment of local lesions, such as abscesses or phlegmons, in an emergent way in the first meeting with the patient. According to the Organization for Economic Co-operation and Development (OECD) reports, Italy is one of countries with a low amputation rate in diabetic patients. Many factors might have contributed to this result, including 1)the special attention directed to diabetes by the public health system, which has defined diabetes as a "protected disease", and accordingly, offers diabetic patients, at no charge, the best specialist care, including specific devices, and 2)the presence of a network of diabetic foot (DF) clinics managed by diabetologists with medical and surgical expertise. The health care providers all share a "patient centred model" of care, for which they use their internal medicine background and skills in podiatric surgery to manage acute or chronic needs in a timely manner. Therefore, according to Italian experiences, which are fully reported in this document, we believe that only a skilled diabetologist/endocrinologist should act as a TL. Courses and university master's degree programmes focused on DF should guarantee specific training for physicians to become a TL.

Treatment of peripheral arterial disease in diabetes: a consensus of the Italian Societies of Diabetes (SID, AMD), Radiology (SIRM) and Vascular Endovascular Surgery (SICVE).

Diabetic foot (DF) is a chronic and highly disabling complication of diabetes. The prevalence of peripheral arterial disease (PAD) is high in diabetic patients and, associated or not with peripheral neuropathy (PN), can be found in 50% of cases of DF. It is worth pointing out that the number of major amputations in diabetic patients is still very high. Many PAD diabetic patients are not revascularised due to lack of technical expertise or, even worse, negative beliefs because of poor experience. This despite the progress obtained in the techniques of distal revascularisation that nowadays allow to reopen distal arteries of the leg and foot. Italy has one of the lowest prevalence rates of major amputations in Europe, and has a long tradition in the field of limb salvage by means of an aggressive approach in debridement, antibiotic therapy and distal revascularisation. Therefore, we believe it is appropriate to produce a consensus document concerning the treatment of PAD and limb salvage in diabetic patients, based on the Italian experience in this field, to share with the scientific community.

Ischemic Charcot foot: different disease with different treatment?

AIM: Aim of the study was to describe the presence of peripheral arterial disease in combination with Charcot neuroarthropathy in diabetic patients, and to evaluate the role of revascularization supporting surgical and orthopedic treatment. METHODS: We retrospectively collected and analyzed data of all diabetic patients affected by Charcot neuroarthropathy in combination with critical limb ischemia, which arrived to our care for the presence of foot lesions and underwent endovascular revascularization, followed by surgical and orthopedic treatment between January 2010 and January 2012. The primary end point was to assess the limb salvage rate. The secondary end point was to evaluate the healing time of the lesions. RESULTS: Ten diabetic patients (10 men; mean age 69.1±8.5 years), affected by ischemic Charcot neuroarthropathy underwent endovascular revascularization, surgical debridement and orthopedic correction. The limb salvage rate was 90%, avoiding major amputation in 9 patients. In one patient (10%) the infection could not be controlled and below-the-knee amputation was carried out. The required time to heal the lesion was in mean 197.4±22.4 days, after revascularization, surgical and orthopedic treatment. CONCLUSION: Patients with Charcot foot deformity can be affected by critical limb ischemia and revascularization therapy is necessary, to support surgical and orthopedic treatment, avoiding amputation and leading to limb and foot salvage.

Is digital arteries recanalization useful to preserve the foot functionality and avoid toes amputation, after pedal recanalization? Clinical results.

AIM: The authors aimed to assess clinical results following percutaneous transluminal angioplasty (PTA) of pedal arteries and digital branches in order to avoid minor amputations or support surgical skin incisions, in patients with CLI and distal wounds on the toes. METHODS: Baseline, procedural and mid-term outcome data of all consecutive patients with CLI and ulcerative lesion on the toes, in which endovascular treatment of the foot arteries and digital branches was attempted, were prospectively collected between January 2010 and January 2011. The primary end-point was acute success (i.e. technical, angiographic and procedural success). Secondary end-points included limb, foot and toes salvage rates, minor amputations, reocclusion/restenosis and repeat treatment. RESULTS: 1057 consecutive patients with CLI were treated and in 24 cases (2.3%), after tibial and foot arteries PTA, related to the presence of arterial lesion (stenosis/occlusion) in the digital branches, the recanalization of the target vessel was performed. Acute technical success was achieved in 100% of cases, with adequate angiographic results without peri-procedural complications. Clinical improvement was obtained and maintained after an average of 9 months. Amputation was avoided in 9 patients (37.5%), in 8 patients (29.6%) amputation involved only a distal phalange, in 5 patients (20.8%) toe amputations was necessary, in 2 patients (8.4%) trans-metatarsal amputation was performed. No below the ankle (BTA) or major amputations were performed. CONCLUSION: Endovascular recanalization of digital branches in patients with CLI and distal wounds on the toes is feasible and safe; represent a support to avoid minor amputations or surgical skin lesion healing.

Clinical results of below-the knee intervention using pedal-plantar loop technique for the revascularization of foot arteries.

AIM: Recent registries and randomized trials support the role of percutaneous revascularization in patients with critical limb ischemia (CLI) due to below-the-knee (BTK) atherosclerotic disease, as percutaneous transluminal angioplasty (PTA) for BTK disease has shown to be feasible and safe in this setting. Nonetheless, succes rates remain suboptimal with current techniques. The authors aimed to appraise clinical results following PTA of foot vessels exploiting a novel technique, based on the recanalization of both pedal and plantar arteries and their anatomical anastomosis in order to restore direct arterial in-flow from both anterior and posterior tibial vessels, defined as the pedal-plantar loop technique. METHODS: Baseline, procedural and mid-term outcome data of all consecutive patients with CLI due to BTK disease in which PTA was attempted using the pedal-plantar loop technique were prospectively collected between January 2007 and September 2008. The primary end-point was acute success (i.e. the composite of technical, angiographic and procedural success). Secondary end-points included limb salvage rate, major (above the ankle) and minor (below the ankle) amputation, change in Rutherford class and transcutaneous oxygen tension, reocclusion/restenosis, rehospitalization, and repeat revascularization after 12 months. RESULTS: A total of 1331 consecutive patients with CLI were treated using BTK PTA and 135 (10.1%) were approached with the pedal-plantar loop technique in order to recanalize the foot arteries. Target lesions were mostly occlusive and diffusely diseased, involving in most cases the tibial arteries as well as the in-flow and out-flow vessels. Acute success was achieved for tibial PTA in 100% of the cases, with ability to position and inflate the balloon and achieve adequate angiographic results without peri-procedural complications in all, whereas acute success for the pedal-plantar loop technique was 85%. Clinical improvement in functional status was obtained and maintained after an average of 12 months, with a significant improvement of transcutaneous oxygen tension after 15 days, 59+/-16 mmHg in the group of patients in which the foot arteries revascularization was successfully feasible, versus 42+/-12 mmHg in patients achieving patency of two BTK vessels at the ankle level with partial out-flow in the foot (P<0.001). CONCLUSIONS: Percutaneous revascularization of foot arteries in patients with CLI is feasible and safe, and appears to provide positive clinical results at both acute and mid-term follow-up.

Simvastatin maintains steady patterns of GFR and improves AER and expression of slit diaphragm proteins in type II diabetes.

The factors determining the course of glomerular filtration rate (GFR) and albumin excretion rate (AER) and the expression of mRNA of slit diaphragm (SD) and podocyte proteins in microalbuminuric, hypertensive type II diabetic patients are not fully understood. GFR, AER, and SD protein mRNA were studied in 86 microalbuminuric, hypertensive, type II diabetics at baseline and after 4-year random double-blind treatment either with 40 mg simvastatin (Group 1) or with 30 g cholestyramine (Group 2) per day. Both groups had at baseline a GFR decay per year in the previous 2-4 years of 3 ml/min/1.73 m(2). Both Groups 1 and 2 showed a significant decrease of low-density lipoprotein cholesterol levels after simvastatin and cholestyramine treatment (P<0.01). No change from base line values was observed as for hs-C-reactive protein and interleukin-6. A significant decrease of 8-hydroxydeoxyguanosine urinary excretion was observed after simvastatin treatment. GFR did not change from baseline with simvstatin, whereas a decrease was observed with cholestyramine treatment (simvastatin vs cholestyramine: -0.21 vs -2.75 ml/min/1.73 m(2), P<0.01). AER decreased in Group 1 (P<0.01), but not in Group 2 patients. Real-time polymerase chain reaction measurement of mRNA SD proteins (CD2AP, FAT, Actn 4, NPHS1, and NPHS2) significantly increased in kidney biopsy specimens after simvastatin, but not cholestyramine treatment. Simvastatin, but not cholestyramine, 4-year treatment maintains steady patterns of GFR, and improves AER and expression of SD proteins in type II diabetes, despite similar hypocholesterolemic effects in circulation.

Evidence of a threshold value of glycated hemoglobin to improve the course of renal function in type 2 diabetes with typical diabetic glomerulopathy.

We recently observed that the course of glomerular filtration rate (GFR) rapidly declines in a subgroup of Type 2 diabetic patients (D) with abnormalities of albumin excretion rate (AER) and typical diabetic nephropathy, despite tight blood pressure control. The aim of this study was to evaluate whether amelioration of blood glucose control, using insulin, improves the course of GFR. GFR decay was measured by spline modeling analysis of the plasma clearance rate of 51CR-EDTA, assessed every 6 months. We identified two groups of D using morphometric analysis of renal biopsy, who had values of glomerular basement membrane (GBM) and fractional mesangial volume (Vv mes/glom) respectively below (Group A: 38) or above (Group B: 50) the mean+2SD of values found in 27 kidney donors (GBM: 389 nm; Vv mes/glom: 0.25), as previously described in detail. Median AER was similar at base line in the 2 groups (109 microg/min, 29-1950, in Group A, 113 microg/min, 37-1845, in Group B; n.s.). Conventional metabolic therapy (sulphonylureas and/or biguanides) was used both in Group A and B during a 3 year follow-up period (Period 1). Group B was further divided in two subgroups with body mass index below (Group B, a) and above (Group B, b) the value of 30 kg/m2. Mean +/- SD HbA1c was 8.2 +/- 1.6% in Group A, 8.3 +/- 1.7% in Group B (a) (n.s.) and 9.1 +/- 1.7% in Group B (b) (n.s.). Tight blood pressure control was achieved and maintained using angiotensin converting enzyme inhibitors and/or beta blockers and/or calcium antagonists and/or thiazides. The mean arterial blood pressure (MAP) was 92 +/- 3 mmHg in Group A and 91 +/- 4 mmHg in Group B (n.s.). GFR decay was significantly greater in Group B than in Group A (Group A vs B: +1.21 +/- 0.71 vs -5.86 +/- 1.61 ml/min/1.73 m2/year). Median AER significantly rose in Group B (177 microg/min, p<0.05 vs base line) but not in Group A (134 microg/min, n.s.) during the third year of follow-up. Groups A and B were then followed over 4.1 years (range 3.1-4.4) (Period 2) maintaining the above described antihypertensive regimen, resulting in MAP values similar to those described during Period 1. Group A patients were treated with the same conventional glycemic control during Period 2. Group B (a) was conversely treated with intensive insulin therapy to achieve a HbA1c value below 7.5% (3 daily injections of regular and 1 or 2 daily injections of intermediate acting insulin associated with metformin 500 mg twice daily in 64% of the patients). Group B (b) patients were only treated by metformin (850 mg thrice daily) to achieve a HbA1c value below 7.5%. HbA1c decreased below the 7.5% target value in Group B (a) (7.0 +/- 1.6%, p<0.01 vs Period 1), but not in Group B (b) (8.0 +/- 1.6%, p<0.05 vs Period 1) and in Group A (8.3 +/- 1.7%, n.s. vs Period 1). The GFR decay of Group B, a during Period 2 was lower than that during Period 1 (Period 1 vs Period 2: -5.9 +/- 1.8 vs -1.8 +/- 0.7 ml/min/1.73 m2/year, p<0.01). GFR decay during Period 2 was similar to that observed during Period 1 in Group A (Period 1 vs Period 2: +1.21 +/- 0.71 vs +0.7 +/- 0.6 ml/min/1.73 ml/year, n.s.) and in Group B (b) (Period 1 vs Period 2: -4.4 +/- 0.71 vs -4.2 +/- 0.6 ml/min/1.73 m2/year, n.s.). Median AER did not significantly change in the fourth year of Period 2 , either in Group A or B (Group A vs B: 141 vs 152 microg/min, n.s.). In conclusion, our findings seem to suggest that amelioration of blood glucose control is attained both by insulin and metformin intensive treatment, but only insulin decreases and maintains HbA1c levels below 7.5%. These pattens of HbA1c appear to be a threshold value in order to significantly blunt GFR decay in a subgroup of Type 2 diabetic patients with typical diabetic glomerular lesions, who are less responsive to tight blood pressure control alone. Conversely, the cohort of patients with less severe diabetic glomerulopathy steadily show constant GFR patterns, despite similar abnormalities of albumin excretion rate, and HbA1c average values above 7.5%.

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.

High plasma prorenin in non diabetic siblings of non insulin-dependent diabetes mellitus patients.

In a large cohort (no. = 361) of NIDDM probands and their concordant/discordant siblings from no. = 132 families we studied: 1. the levels of plasma prorenin in non affected siblings of NIDDM probands as opposed to normal subjects without family history of diabetes, and 2. whether plasma prorenin raises in parallel to urinary protein loss in NIDDM patients. Prorenin (solid-phase trypsin) and micro-macroalbuminuria (radioimmunoassay) were evaluated. Plasma prorenin was higher in NIDDM probands and siblings than in non NIDDM siblings (37+/-31 vs. 25+/-15 ng/ml/h, p<0.0005) who, in turn, showed higher plasma prorenin than non diabetic controls without family history of diabetes (25+/-15 vs. 17+/-8 ng/ml/h, p<0.005). Plasma prorenin was higher in NIDDM siblings of micro-macroalbuminuric probands than in NIDDM siblings of non micro-macroalbuminuric probands (40+/-26 vs. 29+/-20 ng/ml/h, mean +/- SD, p = 0.0058) whereas no difference was found among non diabetic siblings (24+/-14 vs. 22+/-11 ng/ml/h, NS). Our data confirm that plasma prorenin is elevated in NIDDM patients, and show: 1. that the raise of plasma prorenin in non-NIDDM siblings of a diabetic patient does not depend entirely from the presence of diabetes, and 2. that plasma prorenin in NIDDM probands and their concordant siblings goes along with micro-macroalbuminuria.

Renal function in noninsulin-dependent diabetes mellitus patients treated with angiotensin-converting enzyme inhibitors and calcium channel blockers.

BACKGROUND: Data have not shown consistent effects with calcium channel blockers on the course of renal function in patients with noninsulin-dependent diabetes mellitus (NIDDM) who have hypertension alone or in association with renal damage. The differences between the antiproteinuric effects of subclasses or formulations of calcium channel blockers and the heterogeneity of renal lesions may contribute to the discrepancy in these data. Clinical studies conducted by the authors and other recent data that describe the course of renal dysfunction in hypertensive NIDDM patients treated with antihypertensive agents are reviewed. Renal structural changes were also evaluated. RESULTS: Most available data indicate that angiotensin-converting enzyme inhibitors and dihydropyridine and nondihydropyridine calcium channel blockers produce similar effects on glomerular filtration rate. In one study of patients achieving intensified, strict control of blood pressure (target<140/85 mmHg) with either cilazapril or amlodipine, glomerular filtration rate declined by 2.03+/-0.66 ml/ min/1.73 m2 per year and 2.01+/-0.71 ml/min/1.73 m2 per year, respectively, in the subgroup with normoalbuminuria and by 2.15+/-0.69 ml/min/1.73 m2 per year and 2.33+/-0.83 ml/min/ 1.73 m2 per year, respectively, in the subgroup with microalbuminuria. Renal lesions in NIDDM patients were found to be structurally heterogeneous and glomerular filtration rate appeared to decline only in patients with renal structural changes typical of NIDDM. CONCLUSIONS: The extent of blood pressure control, rather than the method by which this is accomplished, is the most important factor in determining the evolution of incipient nephropathy in hypertensive NIDDM. The kidneys of microalbuminuric NIDDM patients are structurally heterogeneous with less than one-third of patients having 'typical' diabetic nephropathology.

Insulin sensitivity and glucose effectiveness: minimal model analysis of regular and insulin-modified FSIGT.

The minimal model is widely used to evaluate insulin action on glucose disappearance from frequently sampled intravenous glucose tolerance tests (FSIGT). The common protocols are a regular (rFSIGT, single injection of 0.3 g/kg of glucose) and an insulin-modified test (mFSIGT, with an additional insulin administration at 20 min). This study compared the insulin sensitivity index (SI) and glucose effectiveness (SG) obtained in the same individual (16 normal subjects) with the two tests. SI was 7.11 +/- 0.80 10(-4).min-1.microU-1.ml in rFSIGT and 6.96 +/- 0.83 in mFSIGT (P = 0.656), regression r = 0.92, P < 0.0001; SG was 0.0260 +/- 0.0028 min-1 and 0.0357 +/- 0.0052, respectively, statistically different (P = 0.013) but still with a good regression (r = 0.66, P = 0.0051). SG and insulin amount during the early period correlated (r = 0.6, P = 0.015 in rFSIGT and r = 0.76, P = 0.0006 in mFSIGT). In summary, both FSIGTs with minimal model analysis provide the same SI, which is a very robust index. SG was different by 28% due probably to the relationship between SG and the amount of circulating insulin. In studies comparing groups, the simpler rFSIGT can still be used with the advantage of accounting for endogenous insulin, thus offering the possibility of direct inferences on the beta-cell activity.

Heterogeneous nature of microalbuminuria in NIDDM: studies of endothelial function and renal structure.

Microalbuminuria (MA) is associated with microangiopathy (renal and retinal lesions) in insulin-dependent diabetic (IDDM) patients. In contrast MA does not reflect microvascular damage in a substantial number of non-insulin-dependent diabetic (NIDDM) patients. MA predicts cardiovascular disease in NIDDM patients with increased von Willebrand factor (vWF) plasma levels which are hypothesized to reflect endothelial dysfunction. However, it is not known whether MA is consequent to generalised endothelial dysfunction or to renal injury. Thus, this study evaluated vWF plasma levels in relation to renal and retinal structural abnormalities in NIDDM patients with MA. Kidney biopsies, fundoscopy and measures of vWF plasma levels were performed in 32 NIDDM patients with MA. These patients were allocated to two renal structural categories: A) Without renal structural abnormalities (C I, n = 10): normal or near-normal renal structure, and B) With renal structural abnormalities (n = 22), further divided into: C II (n = 12) with typical diabetic nephropathology, predominantly glomerulopathy, and C III (n = 10) with atypical patterns of renal injury (more advanced tubulo-interstitial and arteriolar than glomerular changes). vWF plasma levels were significantly higher in category B (C II: 195+/-49% and C III: 161+/-46%) than in category A (C I: 119+/-42%), (chi-square, p < 0.05). Diabetic retinopathy was also related to vWF plasma levels (ANOVA, p < 0.05). These data suggest that there are two types of MA in NIDDM: one associated with increased vWF levels, established renal injury and frequently retinopathy, and the other characterized by normal vWF levels, normal renal structure and absent or mild diabetic retinopathy. We propose that vWF plasma levels in NIDDM patients with MA may help to identify patients with important renal structural changes, increased retinopathy risk and, perhaps, generalised endothelial dysfunction. Whether vWF plasma levels predict end-stage renal disease and cardiovascular events deserves longitudinal studies.

Clustering of albumin excretion rate abnormalities in Caucasian patients with NIDDM. The Italian NIDDM Nephropathy Study Group.

Proteinuria and nephropathy have been found to cluster in families of non-insulin-dependent diabetic (NIDDM) Pima Indian, and in Caucasian insulin-dependent diabetic (IDDM) patients. No information is at present available for Caucasian NIDDM patients. The aim of the present study was to determine whether micro-macroalbuminuria (AER+) is associated with albumin excretion rate abnormalities in diabetic and non-diabetic siblings of probands with NIDDM and AER+. We identified 169 Caucasian families with one NIDDM proband (the patient with longest known NIDDM duration) (101 families with only NIDDM siblings, 33 families with both NIDDM and non-NIDDM siblings and 35 families with only non-NIDDM siblings). Of the probands 56 had AER+ [Prob-NIDDM-(AER+)], 78 had AER-[Prob-NIDDM-(AER-)], 74 siblings of Prob-NIDDM-(AER+), and 113 siblings of Prob-NIDDM-(AER-) also had NIDDM. Data on albuminuria and retinopathy from multiple sibling pairs when the size of the sibship was more than two was adjusted according to a weighting factor. The odds ratio for AER+, in siblings of Prob-NIDDM-(AER+) adjusted for age, hypertension, glycated haemoglobin A1c and other confounding variables was 3.94 (95% confidence intervals: 1.93-9.01) as compared to siblings of Prob-NIDDM-(AER-). The 74 siblings of Prob-NIDDM-(AER+) had higher prevalence of proliferative retinopathy than siblings of Prob-NIDDM-(AER-) (14 vs 2%; p < 0.01). We also identified 66 non-diabetic siblings of 41 NIDDM probands with AER+ and 36 non-diabetic siblings of 27 NIDDM probands with AER-. Albumin excretion was two times higher, although still within the normal range, in the non-diabetic siblings of Prob-NIDDM-(AER+) than in siblings of Prob-NIDDM-(AER-) [median = 13.5 (range 0.5-148) vs 6.6 (range 1-17) micrograms/min (p < 0.05)]. In conclusion higher rates of albumin excretion aggregate in Caucasian families with NIDDM. Proliferative retinopathy is more frequently observed in families showing a clustering of AER+ and NIDDM. These findings suggest that familial factors play a role in the pathogenesis of renal and retinal complications in NIDDM.

Elevated sodium-lithium countertransport activity in erythrocytes is predictive of the development of microalbuminuria in IDDM.

Pathogenetic mechanisms other than the quality of metabolic control may play a role in the development of diabetic nephropathy. Some cross-sectional studies have shown that elevated erythrocyte sodium-lithium countertransport (Na+/Li+ CT) activity may be linked to incipient or overt nephropathy in insulin-dependent diabetic (IDDM) patients. The aim of the present work was to ascertain if high erythrocyte Na+/Li+ CT activity anticipates the development of microalbuminuria in IDDM patients. Evaluation of this cation transport system was carried out in 159 normotensive, normoalbuminuric IDDM patients, who were divided into two groups: those with values above (Group A) and those with values below (Group B) the median level in the overall population (300 mumol/erythrocytes x h). A total of 79 patients in Group A and 80 in Group B underwent periodic examinations over a similar time period (5.2 years, range 3.3-7.4 years and 5.4 years, range 3.4-7.5 years, respectively). Median sodium-lithium countertransport activity was stable when evaluated after 2 and 4 years of follow-up. Only seven patients were excluded from the protocol because changes in their sodium-lithium countertransport activity placed them on the other side of the median value with respect to their baseline measurement. Thus, 152 patients completed the study (76 in Group A and 76 in Group B). Of the 76 patients in Group A, 17 developed persistent microalbuminuria (22.3%). The number of patients in Group B showing persistent microalbuminuria was significantly lower (4 of 76; 5.2%; p < 0.01). The sensitivity of erythrocyte Na+/Li+ CT in predicting the development of microalbuminuria was 85% and its specificity was 55%. Seven patients of Group A and five of Group B developed arterial hypertension. Subjects in Group A had significantly higher mean HbA1c values of twice yearly measurements than those in Group B (9.6 +/- 1.7 vs 8.3 +/- 1.7%, p < 0.002, mean +/- SD) despite similar daily insulin requirements. Systolic and diastolic blood pressure levels were also evaluated every 6 months and were significantly higher in the Group A than in the Group B patients, although on average within the normal range. The odds ratio for developing persistent microalbuminuria in IDDM with elevated baseline erythrocyte Na+/Li+ CT activity after adjustment for gender and baseline albumin excretion rate, and mean 6 monthly plasma creatinine, HbA1c and systolic and diastolic blood pressure levels was 4.2 (95% confidence intervals 2.0-11.1). It was also found that the percentage of offspring having both parents with Na+/Li+ CT activity above the median value was significantly higher in Group A than in Group B (Group A vs Group B: 35 vs 19%; p < 0.01). On the contrary the percentage of offspring whose erythrocyte Na+/Li+ CT was lower in both parents was lower in Group A than in Group B: 10 vs 38%, p < 0.01). Parents of Group A offspring had arterial hypertension more frequently than those of Group B. These results indicate that erythrocyte Na+/Li+ CT activity is a useful diagnostic tool in identifying normotensive, normoalbuminuric patients who may be predisposed to develop persistent microalbuminuria. This disorder in the cation transport system is associated with poor metabolic control, higher blood pressure, and male sex; it also appears to be, at least partly, genetically transmitted.

Relationships among microalbuminuria, insulin resistance and renal-cardiac complications in insulin dependent and non insulin dependent diabetes.

A rate of albumin excretion rate above 20 micrograms/min is a predicting factor of overt nephropathy in Type I diabetes. It has not yet been established whether this is the case also for Type II diabetes, where microalbuminuria is antecedent to general and cardiovascular mortality but not to end-stage renal disease. The reasons accounting for this discrepancy between Type I and Type II diabetes have not been fully elucidated. In principle two different hypotheses can be postulated to explain these findings. Firstly it can be suggested that overt proteinuria is not detected with similar incidence rates in microalbuminuric patients with the two types of diseases because Type II diabetics are older and more prone to develop cardiovascular events. Therefore these patients would die frequently before developing overt proteinuria not because microalbuminuria is not a predicting factor of End-stage Renal Disease, but rather because the follow-up period is not long enough to monitor the patients till the very moment they develop renal complications. Alternatively it is possible that microalbuminuria reflect a systemic, endothelial and vascular disorder rather than glomerular structural abnormalities in these patients. We have recently described a clustering of clinical features encompassing microalbuminuria, hypertension, peripheral extrahepatic insulin resistance, renal and cardiac hypertrophy and altered cation membrane transport systems, not in the overall Type II diabetic population, but only in a cohort of these patients. Evidences in keeping with a strict association between insulin resistance, hypertension and microalbuminuria in a subgroup of Type II diabetic patients have been recently reported by several authors both in cross-sectional and longitudinal studies. However the hypothesis that microalbuminuria reflects a systemic endothelial and vascular disorder in Type II diabetic patients, does not rule out the possibility that these systemic disturbances are also associated with histologic abnormalities of the kidney. With regard to the characteristics of renal histology in Type II diabetic patients with and without microalbuminuria, preliminary data from our laboratory demonstrate that there is no evidence of any renal disorder other than diabetes in microalbuminuric Type II diabetic patients. More particularly in this subset of patients we observed typical features of diabetic nephropathology (glomerular, tubulo-interstitial and arteriolar changes), while a substantial number of patients with increased albumin excretion rate exhibited either marked tubulo-interstitial lesions or arteriolar hyalinosis or both, in absence of significant glomerular changes. These findings suggest that it is not true that Type II diabetic patients with microalbuminuria show quite often normal renal histology, but rather than hyperglycemia may cause different patterns of renal injury as compared to Type I Diabetes. Furthermore always with regard to renal histology, it has been pointed out that in Type I diabetes glomerulopathy (especially mesangial) is the crucial change, whereas recent studies found considerable structural heterogeneity amongst proteinuric Type II diabetic patients with relatively high incidence of renal diseases other than diabetes. However parallel studies in a small group of micromacroalbuminuric Type II diabetic patients reported the typical glomerular changes, usually shown by Type I diabetic patients with similar patterns of renal damage. The issue of the relationships between microalbuminuria, hypertension and the development of overt nephropathy in Type II diabetes has been also examined in Pima Indians. The clinical scenario found in these patients does closely resemble that of Caucasian Type I diabetic patients.

Renal structure and function in non-insulin dependent diabetic patients with microalbuminuria.

We have recently described heterogeneity in renal structure in non-insulin-dependent diabetic patients (NIDDM) with microalbuminuria (MA; defined as albumin excretion rate from 20 to 200 micrograms/min). Thus, at variance with IDDM patients, "typical" diabetic glomerulopathy by light microscopy is observed only in a third of NIDDM with MA (Category II, CII). Further, despite persistent MA, 30% of NIDDM have normal or near normal renal structure (Category I, CI). Another one-third shows "atypical" patterns of renal injury with absent or mild diabetic glomerular changes, associated with disproportionately severe tubulointerstitial lesions and/or arteriolar hyalinosis and global glomerular sclerosis (Category III, CIII). The aims of this study were to evaluate whether similar patterns of renal lesions could be confirmed in a larger group of NIDDM with MA and to investigate tubular function in order to understand the mechanisms underlying MA in NIDDM patients. Renal biopsies were performed in 53 NIDDM with MA. Categories I, II and III were found in 41%, 26% and 33% of NIDDM with MA, respectively. All 8 patients with proliferative diabetic retinopathy were in CII. We also studied the urinary daily excretion rate of alpha 1-microglobulin (alpha 1 m), a low molecular weight protein, which is a useful indicator of tubular function. alpha 1 m was markedly increased only in CII patients (CI vs. CII vs. CIII: 6.2 +/- 1.2 vs. 13.7 +/- 2.1 vs. 7.3 +/- 0.9 mg/day, ANOVA, P < 0.01). In conclusion, we confirm that there is heterogeneity in renal structure in NIDDM patients with MA. This heterogeneity is not due to renal diseases other than diabetes. Increased alpha 1 m and proliferative retinopathy are useful indicators of the subgroup of MA NIDDM patients with typical diabetic glomerulopathy. It is suggested that diabetic microangiopathy explains the simultaneous occurrence of typical diabetic glomerulopathy, proliferative retinopathy and tubular dysfunction in a subgroup of NIDDM patients with MA.

Patterns of renal injury in NIDDM patients with microalbuminuria.

Microalbuminuria predicts overt nephropathy in non-insulin-dependent diabetic (NIDDM) patients; however, the structural basis for this functional abnormality is unknown. In this study we evaluated renal structure and function in a cohort of 34 unselected microalbuminuric NIDDM patients (26 male/8 female, age: 58 +/- 7 years, known diabetes duration: 11 +/- 6 years, HbA1c: 8.5 +/- 1.6%). Systemic hypertension was present in all but 3. Glomerular filtration rate (GFR) was 101 +/- 27 ml.min-1.1.73 m-2 and albumin excretion rate (AER) 44 (20-199) micrograms/ min. Light microscopic slides were categorized as: C I) normal or near normal renal structure; C II) changes "typical" of diabetic nephropathology in insulin-dependent diabetes (IDDM) (glomerular, tubulo-interstitial and arteriolar changes occurring in parallel); C III) "atypical" patterns of injury, with absent or only mild diabetic glomerular changes associated with disproportionately severe renal structural changes including: important tubulo-interstitial with or without arteriolar hyalinosis with or without global glomerular sclerosis. Ten patients (29.4%) were classified as C I, 10 as C II (29.4%) and 14 as C III (41.2%); none of these patients had any definable non-diabetic renal disease. GFR, AER and blood pressure were similar in the three groups, while HbA1c was higher in C II and C III than in C I patients. Diabetic retinopathy was present in all C II patients (background in 50% and proliferative in 50%). None of the patients in C I and C III had proliferative retinopathy, while background retinopathy was observed in 50% of C I and 57% of C III patients. In summary, microalbuminuric NIDDM patients are structurally heterogeneous with less than one third having "typical" diabetic nephropathology. The presence of both "typical" and "atypical" patterns of renal pathology was associated with worse metabolic control, suggesting that hyperglycaemia may cause different patterns of renal injury in older NIDDM compared to younger IDDM patients.