DDOST, PRKCSH and LGALS3, which encode AGE-receptors 1, 2 and 3, respectively, are not associated with diabetic nephropathy in type 1 diabetes.

AIMS/HYPOTHESIS: The AGE receptors 1, 2 and 3, which are encoded by DDOST, PRKCSH and LGALS3, respectively, may be involved in the pathogenesis of diabetic complications. We sought to find out whether these genes are associated with diabetic nephropathy, cardiovascular disease and type 1 diabetes or related quantitative traits. METHODS: Using the Tagger program, we selected 28 single nucleotide polymorphisms (SNPs) based on the HapMap Centre d'Etude du Polymorphisme (Utah residents with northern and western European ancestry) data. The SNPs were genotyped in 2,719 Finnish patients with type 1 diabetes and tested for association with diabetic nephropathy (821 cases, 1,060 controls), cardiovascular disease and related quantitative traits. For association analysis with type 1 diabetes, 703 non-diabetic control participants were genotyped. RESULTS: We found evidence of genotype association between diabetic nephropathy and the SNPs rs2170336 in DDOST (p = 0.03), rs311788 in PRKCSH (p = 0.04) and rs311778 in PRKCSH (p = 0.02). However, these associations did not reach the significance limit of 0.0008 adjusted for multiple testing. None of the DDOST, PRKCSH or LGALS3 SNPs were associated with quantitative traits related to diabetic nephropathy, including AER and estimated GFR. No associations were found between the SNPs and cardiovascular disease, blood pressure, serum lipid levels or type 1 diabetes. CONCLUSIONS/INTERPRETATION: The common SNPs tested in DDOST, PRKCSH and LGALS3 do not seem to be associated with diabetic micro- or macrovascular complications or with type 1 diabetes in Finnish patients.

Increased levels of alpha-defensin (-1, -2 and -3) in type 1 diabetic patients with nephropathy.

OBJECTIVE: Diabetic nephropathy is associated with low-grade inflammation and activation of the complement system. Defensins, as part of the innate immune system, may play a regulatory role in the complement cascade and may also augment the production of proinflammatory cytokines. The aim of this study was therefore to elucidate whether alpha-defensin is associated with diabetic nephropathy, low-grade inflammation and lipid profiles. RESEARCH DESIGN AND METHODS: Data were obtained from 189 patients with type 1 diabetes selected from the FinnDiane Study. Patients were divided into three groups according to their albumin excretion rate (AER) in three consecutive overnight or 24-h urine collections: normoalbuminuria (AER <20 microg/min or <30 mg/24 h), microalbuminuria (20 200 microg/min or >300 mg/24 h). Alpha-defensin was determined by a novel, solid-phase radioimmunoassay (RIA) based on a monoclonal antibody, which recognizes alpha-defensin isoforms 1-3. RESULTS: Total serum alpha-defensin (-1, -2 and -3) concentrations were higher (P < 0.001) in patients with macroalbuminuria compared to micro- and normoalbuminuria, but no difference was observed between normoalbuminuria and microalbuminuria. In multiple linear regression analysis alpha-defensin was associated with systolic blood pressure (P = 0.032), HDL-cholesterol (P = 0.013), total cholesterol (P = 0.008), age (P = 0.001) and estimated glomerular filtration rate (P = 0.001), but not with low-grade inflammatory markers. CONCLUSIONS; Serum alpha-defensin (-1, -2 and -3) concentrations are increased in type 1 diabetic patients with diabetic nephropathy.

Relationship between lipid profiles and kidney function in patients with type 1 diabetes.

AIMS/HYPOTHESIS: We studied the relationship between the lipid profile, estimated GFR (eGFR) and AER in patients with type 1 diabetes. We also assessed the association between the lipid profile and glycaemic control, obesity and hypertension in an environment free of manifest renal disease, as well as exploring how well the patients would have achieved the targets set in international guidelines. METHODS: A total of 2,927 adult patients who had type 1 diabetes and for whom lipid profiles were available were included from people participating in the nationwide, multicentre Finnish Diabetic Nephropathy Study (FinnDiane). eGFR was determined using the Cockcroft-Gault formula adjusted for body surface area. RESULTS: Patients with impaired renal function (eGFR <60 ml min(-1) 1.73 m(-2)) had higher total cholesterol, triacylglycerol and apolipoprotein B, and lower HDL-cholesterol concentrations than patients with normal renal function (eGFR >90 ml min(-1) 1.73 m(-2)) or mildly impaired renal function (eGFR 60-90 ml min(-1) 1.73 m(-2)) (p < 0.001 for all associations). In type 1 diabetic patients without manifest renal disease, similar adverse lipid profiles could be observed in those who were overweight or obese and in those who had intermediate or poor glycaemic control or hypertension. In all the different patient groups 14 to 43% would have achieved the recommended target of <2.6 mmol/l for LDL-cholesterol. CONCLUSIONS/INTERPRETATION: Multiple lipid abnormalities are not only present in type 1 diabetic patients with an abnormal AER, but also in those with impaired renal function. In patients without manifest renal disease, obesity, glycaemic control or hypertension were associated with an adverse lipid profile. A substantial number of patients studied would have exceeded the targets set by international guidelines, particularly the targets for LDL-cholesterol.

The AT2 gene may have a gender-specific effect on kidney function and pulse pressure in type I diabetic patients.

Diabetic nephropathy shows a higher incidence in male subjects, which may in part be owing to genetic factors. The angiotensin II type 2 receptor (AT2), present in the renal glomerulus, may oppose the deleterious effects of the type I receptor (AT1) through vasodilatation and growth inhibition. We determined whether the functional intronic G1675A or A1818T polymorphism of the X-chromosomal AT2 gene is associated with blood pressure levels or with kidney function. We genotyped 996 (538 female/458 male subjects) Finnish patients with type I diabetes from the FinnDiane-study in a cross-sectional study. DNA samples were amplified using standard polymerase chain reaction protocol and the genotypes were determined by the minisequencing method. Male patients with the AA haplotype had a lower glomerular filtration rate (83 +/- 32 vs 94 +/- 34 ml min(-1) 1.73 m(-2), P = 0.008) and a higher pulse pressure (PP) (62 +/- 18 vs 57 +/- 15 mm Hg, P = 0.002; P < 0.05 after adjustment for age) than did those with the GT haplotype. No differences between the genotypes or haplotypes and these variables were evident in females. In males, the G1675A was also an independent variable in a linear regression analysis with PP (r(2) = 0.16, coefficient=3.64, s.e.m.=1.38, P < 0.01) as the dependent variable. These data suggest a gender-specific association between the AT2 gene and kidney function and premature aging of the arterial tree in patients with type I diabetes.

Polymorphisms in the gene encoding angiotensin I converting enzyme 2 and diabetic nephropathy.

AIMS/HYPOTHESIS: Substantial evidence exists for the involvement of the renin-angiotensin system (RAS) in diabetic nephropathy. Angiotensin I converting enzyme 2 (ACE2), a new component of the RAS, has been implicated in kidney disease, hypertension and cardiac function. Based on this, the aim of the present study was to evaluate whether variations in ACE2 are associated with diabetic nephropathy. MATERIALS AND METHODS: We used a cross-sectional, case-control study design to investigate 823 Finnish type 1 diabetic patients (365 with and 458 without nephropathy). Five single-nucleotide polymorphisms (SNPs) were genotyped using TaqMan technology. Haplotypes were estimated using PHASE software, and haplotype frequency differences were analysed using a chi(2)-test-based tool. RESULTS: None of the ACE2 polymorphisms was associated with diabetic nephropathy, and this finding was supported by the haplotype analysis. The ACE2 polymorphisms were not associated with blood pressure, BMI or HbA(1)c. CONCLUSIONS/INTERPRETATION: In Finnish type 1 diabetic patients, ACE2 polymorphisms are not associated with diabetic nephropathy or any studied risk factor for this complication. Further studies are necessary to assess a minor effect of ACE2.

Increased levels of mannan-binding lectin in type 1 diabetic patients with incipient and overt nephropathy.

AIMS/HYPOTHESIS: Diabetic nephropathy is associated with insulin resistance, and low-grade inflammation and activation of the complement system may contribute to this cascade. Mannan-binding lectin (MBL) activates the complement system, and elevated MBL concentrations have been observed in normoalbuminuric type 1 diabetic patients. The aim of this study was to assess whether MBL is associated with diabetic nephropathy in type 1 diabetes, and whether there is an association between MBL and low-grade inflammatory markers or insulin resistance. METHODS: A total of 191 type 1 diabetic patients from the Finnish Diabetic Nephropathy Study were divided into three groups based upon their AER. Patients with normal AER (n=67) did not take antihypertensive medication, while patients with microalbuminuria (n=62) or macroalbuminuria (n=62) were all treated with an ACE inhibitor. As a measure of insulin sensitivity we used estimated glucose disposal rate. MBL was measured by an immunofluorometric assay, C-reactive protein by a radioimmunoassay and IL-6 by high-sensitivity enzyme immunoassay. RESULTS: Patients with normal AER (median [interquartile range]: 1,154 microg/l [180-2,202 microg/l]) had lower levels of MBL than patients with microalbuminuria (1,713 microg/l [724-2,760 microg/l]; p=0.029) or macroalbuminuria (1,648 microg/l [568-3,394 microg/l]; p=0.019). There was a significant correlation between MBL and estimated glucose disposal rate, but not between MBL and C-reactive protein or IL-6 levels in univariate analysis. However, in a multiple regression analysis, HbA1c was the single variable independently associated with MBL (beta+/-SEM: 0.26+/-0.08; p=0.003). CONCLUSIONS/INTERPRETATION: MBL concentrations are increased in type 1 diabetic patients with diabetic nephropathy. MBL was not associated with low-grade inflammatory markers.

Highly elevated serum phyto-oestrogen concentrations in patients with diabetic nephropathy.

BACKGROUND AND OBJECTIVES: Phyto-oestrogens, naturally occurring phenolic, hormone-like compounds, have raised considerable interest due to their anticarcinogenic, antiatherogenic and antioxidative potential. Oxidative stress may be one of the key factors in the development of vascular complications in patients with type 1 diabetes. Here, we tested the hypothesis that high concentrations of phyto-oestrogens in serum may be associated with lower occurrence of vascular complications in these patients. SUBJECTS: A total of 400 patients, recruited consecutively from the participant register of the nationwide FinnDiane study of type 1 diabetes and divided into four parallel groups according to the severity of their renal disease with 100 patients to each group: (i) normoalbuminuric patients, (ii) microalbuminuric patients, (iii) macroalbuminuric patients, and (iv) patients with end-stage renal disease (ESRD). MAIN OUTCOME MEASURES: Phyto-oestrogen concentrations in serum (enterolactone, daidzein, genistein and equol) and urine (enterolactone), assessed by time-resolved fluoroimmunoassay. RESULTS: Highly elevated serum concentrations of phyto-oestrogens were measured amongst patients with diabetic nephropathy, and low concentrations amongst patients without diabetic complications. The pattern was similar for all phyto-oestrogens measured, although the increase in mean serum concentrations along with the increasing severity of renal disease was steepest for enterolactone, ranging from 13 nmol L(-1) amongst women and 18 nmol L(-1) amongst men in normoalbuminuric patients to 181 and 206 nmol L(-1) in women and men, respectively, in patients with ESRD (P < 0.001 for both genders between the groups). A strong correlation between serum enterolactone and creatinine concentration was found (r = 0.60, P < 0.001). CONCLUSIONS: The serum concentration of phyto-oestrogens and the severity of diabetic renal disease showed a close positive association, suggesting that phyto-oestrogens are unable to provide any major protective effect, through antioxidative or other mechanisms, on the development of diabetic renal and cardiovascular complications.

Glucose metabolism in relatives of type 1 diabetic patients with albuminuria.

OBJECTIVE: Diabetic nephropathy in type 1 diabetes is associated with familial aggregation of diabetes. In order to explore the mechanisms behind this association, we assessed glucose metabolism in glucose-intolerant relatives of type 1 diabetic patients with (ALB+) or without (ALB-) elevated urinary albumin excretion rate (UAER). METHODS: Glucose tolerance and insulin secretion were assessed using an oral glucose tolerance test (OGTT) and insulin sensitivity was measured with the short insulin tolerance test (ITT). RESULTS: One hundred and fourteen parents and siblings of 43 type 1 diabetic patients with ALB+ (UAER > or = 20 microg/min) were identified and 93 parents and siblings of 39 patients with ALB- (UAER < 20 microg/min). From this pool, a further selection was made of those (25 and 13 relatives of patients with ALB+ and ALB-, respectively) with mild abnormalities of glucose metabolism (fasting plasma glucose < 7.8 mmol/L; 2 h plasma glucose > or = 7.8 mmol/L in the OGTT). No difference in insulin sensitivity was discernible between the two groups of relatives (KITT 3.3 +/- 1.0 vs. 3.2 +/- 1.0%/min, p=NS). Although there were no significant differences in the incremental areas under glucose or insulin curves (AUC) between relatives of ALB+ and ALB- in the OGTT, the insulin secretory response to the rise in plasma glucose was impaired in relatives of patients with ALB+ (insulin AUC/glucose AUC: 7.1 [1.1-30.8] vs. 9.8 [3.6-52.2], p=0.039). CONCLUSIONS: Glucose-intolerant relatives of patients with elevated UAER seem to be characterized by impaired insulin secretion. Genetic or environmental factors related to impaired insulin secretion may be important in the development of diabetic nephropathy.

Temporal changes in the frequencies of HLA genotypes in patients with Type 1 diabetes--indication of an increased environmental pressure?

AIMS/HYPOTHESIS: The incidence of Type 1 diabetes has increased 2.5 times during the time period from 1966 to 2000 in Finland-a general trend seen in almost all developed countries that can only be explained by environmental factors. The aim of this study was to test the possible effect of a changing environment on distribution of genotypes associated with disease susceptibility. METHODS: HLA DRB1-DQA1-DQB1 genes and two diabetes-associated polymorphisms at IDDM2 and IDDM12 were analyzed. The frequencies of genotypes were compared between cases diagnosed with childhood-onset Type 1 diabetes during the period of 1939-1965 (n=367) and those diagnosed between 1990 and 2001 (n=736). Chi-square statistics or the Fisher's Exact test were used for the comparison of frequencies of analyzed haplotypes and genotypes in the two groups. RESULTS: The frequencies of (DR3) -DQA1*05-DQB1*02 and (DR4) -DQB1*0302 risk haplotypes and the high risk (DR3) -DQA1*05-DQB1*02/DRB1*0401-DQB1*0302 genotype were higher while proportion of patients carrying protective haplotypes-(DR15) -DQB1*0602 and (DR1301) -DQB1*0603-or protective genotypes was lower in patients diagnosed before 1965 as compared to those who developed disease after 1990. No temporal variation was found in the frequencies of genotypes at IDDM2 and IDDM12. CONCLUSION/INTERPRETATION: Our data suggest that the need for genetic susceptibility to develop Type 1 diabetes has decreased over time due to an increasing environmental pressure and this results in a higher disease progression rate especially in subjects with protective HLA genotypes.

No evidence of an exaggerated albuminuric response to physical exercise in non-diabetic siblings of type 1 diabetic patients with diabetic nephropathy.

Substantial evidence suggests a role for genetic factors in the development of diabetic nephropathy in both type 1 and type 2 diabetes. In support of this view, non-diabetic relatives of type 2 diabetic patients with nephropathy have been found to display abnormalities of urinary albumin excretion rate (AER) both when measured at rest and during physical exercise. The aim of the present study was to assess the albuminuric response to physical exercise in non-diabetic relatives of type 1 diabetic patients with nephropathy. AER was measured from urine collections performed (i) overnight, (ii) during an oral glucose tolerance test (OGTT), and (iii) during a submaximal bicycle ergometer test in 21 and 24 non-diabetic siblings of type 1 diabetic patients with (DN+; AER > 200 microg/min) and without diabetic nephropathy (DN-; AER < 20 microg/min). No difference was found in AER (median [range]) measured overnight (DN+ vs DN-: 3.8 [1.3-24.1] vs 3.5 [2.0-21.0] microg/min; P=NS), during the OGTT (DN+ vs DN-: 6.3 [3.2-26.0] vs 4.8 [1.9-15.7] microg/min; P = NS) or during the exercise test (DN+ vs DN-: 44.8 [7.0-535] vs 30.0 [3.4-1614] microg/min; P = NS). In conclusion, we found no evidence of an exaggerated albuminuric response to physical exercise in non-diabetic relatives of type 1 diabetic patients with nephropathy. This differs from previous findings in type 2 diabetes and may suggest differences in the mode of inheritance of albuminuria between type 1 and type 2 diabetes.

Albuminuria in nondiabetic relatives of IDDM patients with and without diabetic nephropathy.

BACKGROUND: In non-insulin-dependent diabetes mellitus (NIDDM), there is a clustering of an elevated urinary albumin excretion rate (U-AER) in nondiabetic relatives of albuminuric patients. Whether this is also the case in insulin-dependent diabetes mellitus (IDDM) is unknown. METHODS: Overnight U-AER was measured in 186 nondiabetic first-degree relatives of 80 IDDM patients with diabetic nephropathy (U-AER > 200 microg/min or 300 mg/24 hours; DN+) and in 52 relatives of 25 IDDM patients without nephropathy (U-AER < 20 microg/min; DN-). The two groups of relatives were comparable regarding gender distribution, age, obesity, blood pressure, prevalence of antihypertensive therapy, and smoking habits. RESULTS: No difference was found in overnight U-AER between relatives of patients with DN+ and DN- [median (range), 3.4 (0.1 to 372) vs. 4.0 (0.2 to 62) microg/min, respectively, P = NS]. The proportion of relatives with a U-AER = 10 microg/min was 12% in DN+ compared with 8% in DN- (P = NS). Among relatives of DN+, those with antihypertensive treatment (AHT+) had higher U-AER compared with those without [AHT+ vs. AHT-, 5.0 (0.5 to 372) vs. 3.4 (0.1 to 26.5) microg/min, P < 0.01], a phenomenon that was not seen among relatives of DN-[AHT + vs. AHT-, 3.6 (2.1 to 24.3) vs. 4.0 (0. 2 to 61.5) microg/min, P = NS]. However, this analysis was impaired by the small number of relatives of DN- with hypertension (N = 7). CONCLUSIONS: In IDDM, we found no clustering of elevated U-AER in nondiabetic relatives of patients with nephropathy. This is different from what has been reported in NIDDM, and suggests heterogeneity in the genesis of albuminuria in diabetes.

The impact of a family history of Type II (non-insulin-dependent) diabetes mellitus on the risk of diabetic nephropathy in patients with Type I (insulin-dependent) diabetes mellitus.

AIMS/HYPOTHESIS: There is substantial evidence for a role of genetic factors in the development of diabetic nephropathy. In Pima Indians, a link between susceptibility to diabetic nephropathy and Type II (non-insulin-dependent) diabetes mellitus has been proposed. In this study, our aim was to examine the association between a family history of Type II diabetes and diabetic nephropathy in patients with Type I (insulin-dependent) diabetes mellitus. METHODS: In a cross-sectional case-control study, we assessed the prevalence of Type II diabetes in the parents of 137 Type I diabetic patients with diabetic nephropathy (albuminuria > 300 microg/min in two of three overnight urine collections) compared with the parents of 54 Type I diabetic patients without nephropathy (albuminuria < 20 microg/min). RESULTS: Thirty-four (25 %) of the patients with nephropathy compared with five (9 %) of the patients without nephropathy had a parental history of Type II diabetes (p = 0.019). A parental history of Type II diabetes was associated with a three-fold risk [odds ratio 2.95 (95% confidence interval: 1.03 to 8.40), p = 0.043] of diabetic nephropathy after adjustment for sex, glycaemic control and family history of hypertension. Furthermore, there was an excess of risk factors for development of Type II diabetes (higher fasting plasma glucose concentrations, higher prevalence of hypertension, higher waist-hip ratio and a tendency towards more glucose intolerance) among previously non-diabetic parents of patients with nephropathy. CONCLUSION/INTERPRETATION: Genetic or environmental factors or both related to familial Type II diabetes increase susceptibility to diabetic nephropathy in patients with Type I diabetes.

Predisposition to essential hypertension and development of diabetic nephropathy in IDDM patients.

Conflicting results have been reported on the relationship between familial predisposition to hypertension and development of diabetic nephropathy in IDDM. In our case-control study, we assessed the prevalence of hypertension among parents of 73 IDDM patients with diabetic nephropathy (DN+; persistent albuminuria > 200 microg/min or > 300 mg/24 h) and 73 IDDM patients without diabetic nephropathy (DN-; urinary albumin excretion < 20 microg/min or < 30 mg/24 h). Arterial hypertension, defined as antihypertensive therapy or a 24-h ambulatory blood pressure (SpaceLabs 90207) > or = 135/85 mmHg, was present in 57% of parents of DN+ patients compared with 41% of parents of DN- patients (P = 0.034; difference 16% [95% CI 1.3-29.6%]). In addition, the cumulative incidence of hypertension was higher among parents of DN+ patients (log-rank test P < 0.001), with a shift toward younger age at onset of hypertension in this group. However, the difference in prevalence of parental hypertension was not evident using office blood pressure measurements (64 vs. 57%; NS; difference 7% [-5.8-20%). Furthermore, patients with DN+ and with antihypertensive therapy in both parents were themselves more frequently treated for hypertension than were patients with DN+ and without parental treatment for hypertension (100 vs. 61%; P = 0.034; difference 39% [21-57%]). In conclusion, familial predisposition to essential hypertension increases the risk of diabetic nephropathy and may also contribute to the development of systemic hypertension in patients with IDDM and diabetic nephropathy.