The angiotensin-converting enzyme DD genotype is associated with glomerulopathy lesions in type 2 diabetes

Nodular glomerulosclerosis and renin angiotensin system in Chinese patients with type 2 diabetes

BACKGROUND

Diabetic nephropathy (DN) is a multifactorial and polygenic disease with nodular glomerulosclerosis (NGS) pathognomonic for diabetes and hypertension. Patients with type 2 diabetes and hypertension have characteristic renin-angiotensin system (RAS) gene polymorphisms.

METHODS AND RESULTS

In this retrospective cohort study, we correlated the presence of NGS with renal function, angiotensin-converting enzyme (ACE) genotypes (DD, DI, and II), angiotensinogen (AGT) genotypes (MM, MT, and TT) and immunohistochemical staining characteristics of RAS components in 847 patients and 172 consecutive autopsy cases with type 2 diabetes. T allele of AGT was associated with macroalbuminuria (P = 0.040). Multitude regression analysis revealed ACE insertion (I)/deletion (D) polymorphism as an independent determinant for estimated glomerular filtration rate (eGFR) less than 60 mL min(-1)·1.73 m(-2) (DD carriers: odds ratio [OR] = 3.46, 95% confidence interval [CI] = 1.08-11.07; DI carriers: OR = 3.51, 95% CI = 1.63-7.56). A significant association between NGS and eGFR less than 60 mL min(-1)·1.73 m(-2) also persisted after adjusting for nonlinear relationship (P < 0.001). In NGS patients, immunoreactivity of angiotensin I converting enzyme 2 (ACE2) significantly decreased in glomeruli with mesangial nodules compared with glomeruli without the mesangial nodules.

CONCLUSIONS

These data suggest associations of ACE D allele with glomerular filtration impairment, and NGS with glomerular ACE2 down-regulation and reduced glomerular filtration in Chinese patients with type 2 diabetes.

Genetic Predisposition to Diabetic Nephropathy: Evidence for a Role of ACE (I/D) Gene Polymorphism in Type 2 Diabetic Population from Kutch Region

Genetic polymorphism as described with angiotensin-converting enzyme gene has been proposed as a putative mediator of diabetic nephropathy. We substantiate the hypothesis that genetic variants of the ACE have significant impacts on diabetic nephropathy. To assess the possible association between the three ACE polymorphic variants and DN in an ethnically homogeneous type 2 diabetic population from Kutch region. A 287-bp insertion/deletion polymorphism in intron 16 of the ACE gene was examined by polymerase chain reaction using a case-control approach conducted with 309 unrelated type 2 diabetic patients of Kutch origin (159 Ahir and 150 Rabari, with >10 years duration of T2DM). Of the patients, 143 had nephropathy {AER >30 mg/day (Ahir, n:73 and Rabari, n:70)} and were considered as cases; all others {n:166 (86 Ahir and 80 Rabari)} were normoalbuminuric (AER <30 mg/day) and were treated as controls. Suitable descriptive statistics was used for different variables. Genotype frequencies in all groups were all in accordance with the Hardy-Weinberg equilibrium. Genotypic distribution was significantly different between cases and controls (Ahir: x(2) :8.87, 2 d.f. p = 0.0118; Rabari: x(2) :11.01, 2 d.f. p = 0.0041). Multivariate logistic regression analysis revealed that DD genotype was a significant and strongest independent predictor of microalbuminuria (Ahir: p = 0.0362, OR = 2.65, 95 % CI 1.89-6.36; Rabari: p = 0.024, OR = 2.81, 95 % CI 1.9-6.65). However, it did not independently change the odds of having macroalbuminuria versus microalbuminuria. Analysis of the association under various genetic models revealed that ACE I/D polymorphic variant contribute to DN susceptibility under recessive mode only. Genetic variation at the ACE locus as D/D variant in intron 16, contribute to an increased risk of nephropathy in T2DM patients but not extent of DN severity, and thus this polymorphism might be considered as genetic risk factors for DN among patients with type 2 diabetes.

Biomarkers for early diagnosis of type 2 diabetic nephropathy: a study based on an integrated biomarker system

Diabetic nephropathy is a devastating disease that affects a growing number of diabetic patients. A complete cure is very hard to achieve once the disease has been diagnosed, therefore the diagnosis of early stages in diabetic nephropathy has become a hot area. Numbers of molecules have been proposed to be potential biomarkers for this purpose. However, some problems still remain, such as discovering effective biomarkers to diagnose the disease before obvious clinical evidence appears. Thus, the main purpose of this study was to find plasma biomarkers for early diagnosis of type 2 diabetic nephropathy stage 1 and stage 2, as well as separating them from diabetes. 182 subjects (Chinese) were recruited for this study, including 50 healthy controls, 33 type 2 diabetic patients and 99 type 2 diabetic nephropathy patients (33 of these were stage 3). Important clinical indicators including proteinuria, serum creatinine, and urea nitrogen were measured and the glomerular filtration rate was estimated to assess kidney function; fasting blood glucose, postprandial blood glucose and glycated hemoglobin were measured to assess the blood glucose control. Key metabolites and genes in plasma samples were identified and determined using -omic and quantitative techniques. The potential biomarkers were then combined and carefully screened to determine the most informative ones for early diagnosis of type 2 diabetic nephropathy. An integrated biomarker system (IBS) incorporating 6 clinical indicators, 40 metabolites and 5 genes was established. Correlation analysis results revealed that most of the potential biomarkers significantly correlated with the 6 clinical indicators. Discriminant analysis results showed that the developed IBS gave the highest total predictive accuracy (98.9%). Significant test and receiver operating characteristic analysis results indicated that inosine had the highest sensitivity (0.889), specificity (1.000), positive predictive rate (1.000) and negative predictive rate (0.900) amongst the 48 potential biomarkers when separating patients with diabetes from patients with diabetic nephropathy stage 3. Finally, inosine with a cutoff of 0.086 mg L(-1) was combined with estimated GFR to differentiate between diabetic nephropathy stages 1 and 2 from diabetes. The results demonstrate that IBS combined with a proper statistical analysis technique is a powerful tool for biomarker screening.

DD genotype of angiotensin-converting enzyme in type 2 diabetes mellitus with renal disease in Mexican Mestizos

AIM

The DD genotype of angiotensin-converting enzyme (ACE) has been suggested as a major contributor of diabetic nephropathy in several populations. The purpose of the present study was to determine whether micro/macroalbuminuria is associated with ACE insertion/deletion (I/D) polymorphism in Mexican Mestizos with type 2 diabetes mellitus.

METHODS

A total of 435 patients with type 2 diabetes mellitus, of whom 233 had albuminuria, were characterized for the ACE I/D polymorphism by the polymerase chain reaction method.

RESULTS

Clinical and biochemical characteristics and frequencies according to DD, ID and II genotypes in patients with and without albuminuria showed no significant differences. However, only females with micro/macroalbuminuria showed higher frequency of a DD genotype than those without albuminuria (27.9%, 21.2% and 10.5%, respectively; P <or= 0.044). In addition, female patients with macroalbuminuria without dialysis showed no significant differences with patients undergoing dialysis.

CONCLUSION

The ACE DD genotype is a risk factor for the development of renal disease in Mexican Mestizo females with type 2 diabetes, indicating a possible DD genotype-associated sex effect in renal disease.

Diabetic nephropathy in children and adolescents

Type 1 diabetes mellitus (T1DM) commonly occurs in childhood or adolescence, although the rising prevalence of type 2 diabetes mellitus (T2DM) in these age groups is now being seen worldwide. Diabetic nephropathy (DN) develops in 15-20% of subjects with T1DM and in similar or higher percentage of T2DM patients, causing increased morbidity and premature mortality. Although overt DN or kidney failure caused by either type of diabetes are very uncommon during childhood or adolescence, diabetic kidney disease in susceptible patients almost certainly begins soon after disease onset and may accelerate during adolescence, leading to microalbuminuria or incipient DN. Therefore, all diabetics warrant ongoing assessment of kidney function and screening for the earliest manifestations of renal injury. Pediatric health care professionals ought to understand about risk factors, strategy for prevention, method for screening, and treatment of early DN. This review considers each form of diabetes separately, including natural history, risk factors for development, screening for early manifestations, and strategy recommended for prevention and treatment of DN in children and adolescents.

ACE gene polymorphism and losartan treatment in type 2 diabetic patients with nephropathy

Losartan treatment reduced renal outcomes in proteinuric patients with type 2 diabetes in the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study. It is unknown whether an insertion (I)/deletion (D) polymorphism in the angiotensin I-converting enzyme (ACE) gene predicts renal outcomes and death and influences the effect of losartan in these patients. Pharmacogenetic analyses were performed comparing losartan with placebo administered with conventional blood pressure-lowering therapy in 1435 (95%) of the 1513 RENAAL study patients. The primary endpoint was the composite of doubling of baseline serum creatinine concentration, end-stage renal disease (ESRD) or death. Cox regression models were stratified on baseline proteinuria and included treatment, geographic region, ACE/ID genotype, and treatment x genotype interaction. Within the placebo group, subjects with the ID or DD genotype were more likely than those with the II genotype to reach the composite endpoint (by 17.5% and 38.1%, respectively, P = 0.029) or its individual components. Within the losartan group, genotype did not correlate with reaching the composite endpoint. Compared with placebo, however, losartan reduced the risk of reaching the composite endpoint by 5.8% (95% confidence interval, -23.3, 28.0), 17.6% (3.8, 29.4), and 27.9% (7.0, 44.1) among those with the II, ID, and DD genotypes, respectively. Similar trends were demonstrated for the individual endpoints. In conclusion, proteinuric type 2 diabetic patients with the D allele of the ACE gene have an unfavorable renal prognosis, which can be mitigated and even improved by losartan.

Lack of association between the angiotensin-converting enzyme gene (I/D) polymorphism and diabetic nephropathy in Tunisian type 2 diabetic patients

Objective. The aim of the present study was to investigate whether the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism is associated with diabetic nephropathy and type 2 diabetes in the Tunisian population.

Design. A case-control study was conducted among 141 unrelated type 2 diabetic patients with (90 patients) or without nephropathy (51 patients) and 103 non-diabetic controls with normal fasting blood glucose. Genotyping was performed using a nested polymerase chain reaction amplification in order to identify correctly heterozygous individuals.

Results. The distribution of DD, ID and II genotypes did not significantly differ between type 2 diabetic patients with or without nephropathy (DD: 44%; ID: 46%; II: 10% vs. DD: 41%; ID: 47 %; II: 12%, respectively).There was also no significant statistical difference between the genotype distribution and allele frequencies of the (I/D) polymorphism in all type 2 diabetic subjects compared to non-diabetic controls with normal fasting blood glucose (DD: 43%; ID: 46%; II: 11% vs. DD: 37%; ID: 48% ;II: 15%, respectively).

Conclusions. In the present preliminary study, the (I/D) polymorphis within the ACE gene is likely not associated with diabetic nephropathy nor with type 2 diabetes in the Tunisian studied population.

Histopathology of diabetic nephropathy

The clinical manifestations of diabetic nephropathy, proteinuria, increased blood pressure, and decreased glomerular filtration rate, are similar in type 1 and type 2 diabetes; however, the renal lesions underlying renal dysfunction in the 2 conditions may differ. Indeed, although tubular, interstitial, and arteriolar lesions are ultimately present in type 1 diabetes, as the disease progresses, the most important structural changes involve the glomerulus. In contrast, a substantial subset of type 2 diabetic patients, despite the presence of microalbuminuria or proteinuria, have normal glomerular structure with or without tubulointerstitial and/or arteriolar abnormalities. The clinical manifestations of diabetic nephropathy are strongly related with the structural changes, especially with the degree of mesangial expansion in both type 1 and type 2 diabetes. However, several other important structural changes are involved. Previous studies, using light and electron microscopic morphometric analysis, have described the renal structural changes and the structural-functional relationships of diabetic nephropathy. This review focuses on these topics, emphasizing the contribution of research kidney biopsy studies to the understanding of the pathogenesis of diabetic nephropathy and the identification of patients with a higher risk of progression to end-stage renal disease. Finally, evidence is presented that the reversal of established lesions of diabetic nephropathy is possible.

The impact of the angiotensin-converting enzyme insertion/deletion polymorphism on severe hypoglycemia in Type 2 diabetes

The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme gene (ACE) is associated with altered serum ACE activity. Raised ACE levels and the ACE DD genotype are associated with a 3.2 to 6.8-fold increased risk of severe hypoglycemia in type 1 diabetes. This relationship has not been assessed in type 2 diabetes. We aimed to test for association of the ACE I/D polymorphism with severe hypoglycemia in type 2 diabetes. Patients with type 2 diabetes (n = 308), treated with insulin (n = 124) or sulphonylureas (n = 184), were classified according to whether or not they had previously experienced severe hypoglycemia. Samples of DNA were genotyped for the ACE I/D polymorphism using two alternative polymerase chain reactions to prevent mistyping due to preferential amplification of the D allele. Overall, 12% of patients had previously experienced one or more episodes of severe hypoglycemia. This proportion did not differ between genotype groups (odds ratio (95% confidence limits) for carriers of D allele relative to II homozygotes: 0.79 (0.35-1.78)). This study found no evidence for association of the ACE I/D polymorphism with severe hypoglycemia frequency in patients with type 2 diabetes. However, we cannot rule out a smaller effect (odds ratio </= 1.78). Our results suggest that any effect of ACE genotype on severe hypoglycemia risk in type 2 patients is likely to be smaller than that seen in type 1 diabetes. We recommend future larger-scale studies.

Preventing end stage renal disease in diabetic patients--genetic aspect (part I)

Diabetic nephropathy is a major cause of diabetes- related morbidity and mortality; however the clinical course of the disease and the renal prognosis is highly variable among individuals. The current review will discuss the genetic influence on the development of end stage renal disease (ESRD) in diabetic patients and potential improvements to the current treatment strategy to slow the loss of kidney function in these patients. In this first part, the growing evidence that glucose-induced activation of the intra-renal and systemic renin-angiotensin systems plays an essential role in processes leading to destruction of renal function is summarised. Genetic variations, especially the angiotensin-converting enzyme (ACE)/ID polymorphisms in the gene coding for ACE, are involved in activation of the renin-angiotensin system and seem to influence the clinical course of diabetic nephropathy during treatment with ACE inhibitors. In addition, this polymorphism may interact with other polymorphisms within the renin-angiotensin system, leading to high risk of ESRD. As new genetic approaches and methods develop, further understanding of diabetic nephropathy will evolve and genotyping will help prevent ESRD in diabetic patients.

Association of angiotensin-converting enzyme DD genotype with 24-h blood pressure abnormalities in normoalbuminuric children and adolescents with Type 1 diabetes

AIMS

To assess the distribution of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene in children and adolescents with Type 1 diabetes and to evaluate the association between ACE genotype and blood pressure (BP).

METHODS

ACE genotypes were assessed in 124 normoalbuminuric, clinically normotensive Type 1 diabetic children and adolescents and 120 non-diabetic controls using polymerase chain reaction. Twenty-four-hour ambulatory BP monitoring was undertaken in all patients.

RESULTS

ACE genotypes distributed in patients as follows: 34 (27%) DD, 57 (46%) ID, 33 (27%) II. The distribution was similar in the control group: DD in 28% (33), ID in 45% (54), and II in 27% (33). Patients with DD genotype had higher mean 24-h diastolic BP (73.8 +/- 6.2 vs. 70.2 +/- 5.0 and 69.7 +/- 6.3 mmHg; P = 0.005) and lower diurnal variation in BP (11.8 +/- 4.6 vs. 14.2 +/- 4.2 and 14.8 +/- 4.3%; P = 0.011) compared with ID and II groups. Four patients in the DD group proved to be non-dipper compared with one in the ID and none in the II group (P = 0.026). Twenty-four-hour diastolic blood pressure was independently predictive for AER as dependent variable in the DD genotype patient group (r(2) = 0.12, P = 0.03).

CONCLUSIONS

Children and adolescents with Type 1 diabetes do not differ from the non-diabetic population regarding the I/D polymorphism of the ACE gene. ACE gene polymorphism is associated with BP abnormalities in normotensive and normoalbuminuric children and adolescents with Type 1 diabetes.

Putative roles of kinin receptors in the therapeutic effects of angiotensin 1-converting enzyme inhibitors in diabetes mellitus

The role of endogenous kinins and their receptors in diabetes mellitus is being confirmed with the recent developments of molecular and genetic animal models. Compelling evidence suggests that the kinin B(2) receptor is organ-protective and partakes to the therapeutic effects of angiotensin 1-converting enzyme inhibitors (ACEI) and angiotensin AT(1) receptor antagonists. Benefits derive primarily from vasodilatory, antihypertensive, antiproliferative, antihypertrophic, antifibrotic, antithrombotic and antioxidant properties of kinin B(2) receptor activation. Mechanisms include the formation of nitric oxide and prostacyclin and the inhibition of NAD(P)H oxidase activity involving classical and novel signalling pathways. Kinin B(2) receptor also ameliorates insulin resistance by increasing glucose uptake and supply, and by inducing glucose transporter-4 translocation either directly or through phosphorylation of insulin receptor. The kinin B(1) receptor, which is induced by the cytokine network, growth factors and hyperglycaemia, mediates hyperalgesia, vascular hyperpermeability and leukocytes infiltration in diabetic animals. However, emerging data highlight reno- and cardio-protective effects mediated by kinin B(1) receptor under chronic ACEI therapy in diabetes mellitus. Thus, the Janus-faced of kinin receptors needs to be taken into account in future drug development. For instance, locally acting kinin B(1)/B(2) receptor agonists if used in a safe therapeutic window may represent a more rationale strategy in the prevention and management of diabetic complications. Because kinin B(2) receptor antagonists may further increase insulin resistance, the persisting dogma that restricts the development of kinin receptor analogues to antagonists (that is still relevant to abrogate pain and inflammation) needs to be revisited.

Predicting the development of diabetic nephropathy and its progression

Diabetes remains the number one cause of end-stage renal disease worldwide. Only about one third of diabetic patients develop nephropathy, and the risk appears to be, in part, genetically determined. In this article, we review clinical and genetic markers for the development and progression of diabetic nephropathy. Microalbuminuria remains the best available predictor of the subsequent development of nephropathy, even though in recent years it has become clear that less than 50% of individuals with type 1 diabetes progress to overt proteinuria over a period of less than 10 years. It is of great interest for early recognition of risk of nephropathy that small elevations in nighttime blood pressure predict microalbuminuria in type 1 diabetes. Genetic markers for diabetic nephropathy have not been conclusively identified. The occurrence of renal events in diabetic patients, however, appears to be influenced by the angiotensin-converting enzyme (ACE) genotype, with a dominant deleterious effect of the D allele (D/D or I/D) versus I/I genotype. Some patients with the DD genotype also appear less susceptible to the renoprotective effects of conventional doses of ACE inhibitors, suggesting that ACE genotyping might be useful in selecting those patients that could benefit from higher doses of ACE inhibitors and more aggressive treatment to prevent or delay disease progression.

Prognostic effect of insertion/deletion polymorphism of the ace gene on renal and cardiovascular clinical outcomes in Chinese patients with type 2 diabetes

OBJECTIVE

The insertion/deletion (I/D) polymorphism of the ACE gene has been reported to be associated with diabetic microvascular or macrovascular complications. The aim of the present study was to investigate the prognostic effect of I/D polymorphism on renal and cardiovascular clinical outcomes in Chinese patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A consecutive cohort of 1,281 Chinese patients with type 2 diabetes were followed for 41.3 +/- 21.6 months. Renal end points were defined as renal death and events (need for dialysis, plasma creatinine >/=500 micromol/l, or doubling of plasma creatinine of baseline value >/=150 micromol/l). Cardiovascular end points were defined as cardiovascular death and events, which included ischemic heart disease, heart failure, cerebrovascular accident, and revascularization requiring hospital admission. The I/D polymorphism of the ACE gene was examined by PCR followed by agarose gel electrophoresis.

RESULTS

The frequencies of ACE gene I/D polymorphisms were in Hardy-Weinberg equilibrium. Patients who developed a renal end point (n = 98) had higher frequencies of DD genotype (19.4 vs. 10.8%, P = 0.018) and D allele (41.3 vs. 31.8%, P = 0.006) compared with subjects who did not (n = 1,183). The cumulative rates of renal end points were 10.0, 19.2, and 24.4% in the II (n = 595), DI (n = 539), and DD genotype carriers (n = 147), respectively (log rank P = 0.004). In multiple Cox regression analysis, the occurrence of renal end points remained significantly influenced by I/D polymorphism with a dominant deleterious effect of the DD genotype (DD versus II, adjusted hazard ratio 2.80 [95% CI 1.49-5.29]). There was no prognostic effect of I/D polymorphism on cardiovascular end points.

CONCLUSIONS

The DD genotype of the ACE I/D polymorphism was an independent risk factor for renal but not cardiovascular end points in Chinese patients with type 2 diabetes.

Diabetic nephropathy: diagnosis, prevention, and treatment

Diabetic nephropathy is the leading cause of kidney disease in patients starting renal replacement therapy and affects approximately 40% of type 1 and type 2 diabetic patients. It increases the risk of death, mainly from cardiovascular causes, and is defined by increased urinary albumin excretion (UAE) in the absence of other renal diseases. Diabetic nephropathy is categorized into stages: microalbuminuria (UAE >20 microg/min and < or =199 microg/min) and macroalbuminuria (UAE > or =200 microg/min). Hyperglycemia, increased blood pressure levels, and genetic predisposition are the main risk factors for the development of diabetic nephropathy. Elevated serum lipids, smoking habits, and the amount and origin of dietary protein also seem to play a role as risk factors. Screening for microalbuminuria should be performed yearly, starting 5 years after diagnosis in type 1 diabetes or earlier in the presence of puberty or poor metabolic control. In patients with type 2 diabetes, screening should be performed at diagnosis and yearly thereafter. Patients with micro- and macroalbuminuria should undergo an evaluation regarding the presence of comorbid associations, especially retinopathy and macrovascular disease. Achieving the best metabolic control (A1c <7%), treating hypertension (<130/80 mmHg or <125/75 mmHg if proteinuria >1.0 g/24 h and increased serum creatinine), using drugs with blockade effect on the renin-angiotensin-aldosterone system, and treating dyslipidemia (LDL cholesterol <100 mg/dl) are effective strategies for preventing the development of microalbuminuria, in delaying the progression to more advanced stages of nephropathy and in reducing cardiovascular mortality in patients with type 1 and type 2 diabetes.

ACE and AT1 receptor gene polymorphisms and renal scarring in urinary bladder dysfunction

The objective of this study was to investigate whether DNA polymorphisms of the renin-angiotensin system (RAS) genes were associated with renal scar formation in pediatric patients with bladder dysfunction (BD). Although these children are born healthy, due to persistence of immature voiding habits and evolution of BD, some develop progressive renal damage. It has been suggested that the DD genotype of the angiotensin I-converting enzyme (ACE) gene might be an adverse renal prognostic factor. The insertion/deletion (I/D) polymorphism of the ACE gene and the A1166C polymorphism of the angiotensin II type 1 receptor (ATR1) gene were identified by polymerase chain reaction amplification in 42 children with BD (aged 5-14 years) and 198 healthy adult controls. Twelve children had urgency syndrome and 30 had dysfunctional voiding. Renal scarring was found in 16 patients, while 26 patients had normal kidneys on dimercaptosuccinic acid scan. In children with renal lesions there was significant over-representation of the DD genotype compared with either controls or patients without renal damage ( P<0.05). On multivariate analysis, the DD genotype was the only factor that had a significant impact on renal scar formation, introducing a 2.51-fold risk (odds ratio 2.51, 95% confidence interval 1.04-6.04, P=0.04). The A1166C gene polymorphism was not significantly associated with the development of parenchymal damage in children with BD. Our findings introduce ACE I/D gene polymorphism as an independent risk factor for parenchymal destruction in pediatric patients with BD.

Development of diabetes mellitus several years after manifestation of diabetic nephropathy: case report and review of literature

OBJECTIVE

To describe an unusual case of development of diabetes mellitus (DM) several years after manifestation of diabetic nephropathy and to review the related literature.

METHODS

We present a case report, including detailed laboratory and pathologic findings in a 51-year-old man who was diagnosed as having DM several years after presenting with diabetic nephropathy. The pertinent literature is also reviewed.

RESULTS

A 51-year-old African American man presented with proteinuria of 4 g/24 h. Past medical history was significant for impaired glucose tolerance diagnosed 2 years previously. Subsequent follow-up demonstrated fasting blood glucose levels ranging from 108 to 123 mg/dL and glycated hemoglobin levels ranging from 5.3 to 5.8%. The patient also had chronic hepatitis C, hypertension, a history of intravenous drug abuse, and a family history of DM and hypertension. On examination of the patient, his blood pressure was 180/90 mm Hg. Funduscopy revealed mild diabetic retinopathy. Work-up was negative for glomerulonephritis, connective tissue disease, vasculitis, or multiple myeloma. Kidney biopsy revealed thickened glomerular basement membranes and diffuse glomeru-losclerosis, consistent with diabetic nephropathy. During follow-up, 9 years after presenting with proteinuria and 4 years after diagnosis of biopsy-proven diabetic nephropathy, the patient had a blood glucose level of 890 mg/dL and diabetic ketoacidosis.

CONCLUSION

This case provides one explanation for the natural course of patients who present with "diabetic complications" but have no diabetes. Some of those patients may have "prediabetes" and may manifest with DM during follow-up. We also conclude that hyperglycemia is not the only important factor in the pathogenesis of diabetic nephropathy.

Angiotensin-Converting Enzyme Genotype in Blacks with Diabetic Nephropathy: Effects on Risk of Diabetes and Its Complications

Objective

Among blacks, we have observed that diabetic nephropathy (DN) is a more frequent primary cause of end-stage renal disease (ESRD) in women (∼ 50%) than in men (< 20%). In this study, we consider the role of the angiotensin-converting enzyme (ACE) polymorphism in determining this gender discrepancy and its role in the course of DN.

Methods

ACE genotype (I = insertion, D = deletion) was determined in consecutive consenting patients with type 2 diabetes mellitus and DN. Charts were subsequently reviewed for renal survival and its determinants (end point: time to ESRD from first clinic visit).

Results

Fifty-four patients (46 blacks) who had DN and were pre-ESRD consented: II = 6, ID = 31, and DD = 17. The allele frequency for D was ∼. 61 versus .39 for the I allele and did not differ by gender. Renal disease at presentation to the renal clinic was significantly worse in II. Twenty-one patients reached ESRD (II = 4, ID = 13, DD = 4; χ2 not significant), but ACE genotype had no significant effect on renal survival. Initial serum creatinine and blood pressure over follow-up independently predicted renal survival. Among blacks reaching ESRD, the presence of the D allele was associated with higher blood pressures. Patients without a family history of diabetes (χ2, p = .01) or diabetic retinopathy (χ2, p = .02) were more likely to have the DD genotype.

Conclusions

The gender discrepancy observed in rates of ESRD owing to DN in blacks is not likely dependent on ACE genotype. The effects of ACE genotype on renal disease progression were not significant; however, patients with diabetic nephropathy and DD genotype were less likely to have traditional risk factors for diabetes or diabetic nephropathy.

Genetic Variation in the Renin-Angiotensin System and Progression of Diabetic Nephropathy

ABSTRACT. The impact of polymorphisms in the genes coding for angiotensinogen (M235T), ACE (ID), and angiotensin II type 1 receptor (A1166→C) on decline in GFR and doubling of s-creatinine or development of ESRD in patients with type 1 diabetes and diabetic nephropathy (DN) was tested. From 1985, all patients (n= 169) who had established diabetic nephropathy and were treated with angiotensin-converting enzyme inhibition (ACE-I) were identified consecutively at Steno Diabetes Center. Patients were followed for a median of 6 yr (range, 3 to 15 yr), with nine (range, three to 29) measurements of GFR (51Cr-EDTA). In a Cox proportional hazards model corrected for other risk factors, theDallele (ACE/ID) was associated with time to doubling of s-creatinine/ESRD (rate ratio, 1.81 per allele; 95% confidence interval, 1.09 to 3.03;P= 0.02). A new interaction hypothesis was generated demonstrating that the following variables were associated with accelerated decline in GFR: albuminuria (estimate, 2.12 ml/min per yr per 10-fold increase in albuminuria;P< 0.001), mean BP (estimate, 0.88 ml/min per yr per 10 mmHg;P= 0.02), hemoglobin A1c(estimate, 0.54 min/min per yr per 1%;P= 0.02), and number ofM(M235T)/D(ID)/A(A1166→C) alleles (estimate, 0.45 ml/min per yr per allele;P= 0.049). Number ofM/D/Aalleles also influenced time to doubling of s-creatinine or ESRD. In this study of patients with type 1 diabetes, theDallele of theACE/IDpolymorphism in addition to nongenetic risk factors independently accelerated progression of DN during ACE-I. Interaction between polymorphisms in the renin-angiotensin system also influenced the loss of kidney function. This new genetic interaction model needs to be confirmed in future studies. E-mail: pkjacobsen@dadlnet.dk

Angiotensin-converting enzyme gene polymorphism as a potent risk factor for developing microalbuminuria in Japanese patients with type 2 diabetes mellitus: a 9-year follow-up study

To clarify the risk factors for developing microalbuminuria in patients with type 2 diabetes mellitus, a longitudinal observational study was performed. Fifty patients with normoalbuminuria were recruited and treated conventionally for 9 years. Polymorphisms of the angiotensin-converting enzyme (ACE) gene and the angiotensinogen M235T polymorphism were examined. During the study period, 12 of the 50 patients developed microalbuminuria; no patients progressed to macroalbuminuria. Multiple logistic regression analysis was performed using age, duration of diabetes, body mass index, haemoglobin A1c' blood pressure, serum lipid profile and genetic polymorphisms as independent variables and development of microalbuminuria as the dependent variable. The D allele of the ACE gene was an independent and significant variable. We conclude that the ACE gene D allele polymorphism is a potent risk factor for developing microalbuminuria in type 2 diabetic patients.

Diabetes and nephropathy

PURPOSE OF REVIEW

Diabetic nephropathy is the single most common disorder leading to renal failure. Its annual incidence has more than doubled in the past decade to reach 44% of all end-stage renal disease, despite recent therapeutic advances. Thus, research into diabetic nephropathy pathophysiology that could lead to new treatment approaches is urgently needed and this review aims to summarize the work performed in this area in the past year.

RECENT FINDINGS

There have been advances in the understanding of diabetic nephropathy pathology. Clearly, structural changes may be advanced before any clinical findings are apparent. Not all functional consequences of the condition are explained by current structural analyses. Genetic studies have connected the disorder risk to multiple candidate genes and a few genetic loci, but the exact genetic predisposition or protectors are not fully described. Perturbations in multiple metabolic pathways are associated with diabetic nephropathy in animals and humans, but their relative importance requires further work. Glycemia and blood pressure control are crucial for diabetic nephropathy prevention and treatment, but new modalities are needed.

SUMMARY

Recent advances in molecular biology and genetics will bring new insights to the mechanisms involved in diabetic nephropathy development. This will allow early identification of patients at risk of, or safe from, diabetic nephropathy and will hopefully lead to preventive strategies, based on the understanding of the pathophysiology of the disorder. Meanwhile, aggressive implementation of proven therapies to prevent (glycemic control) and slow (antihypertensive therapy, especially with renin-angiotensin system blockers) the progression of diabetic nephropathy are strongly recommended.

Long-term renoprotective effects of losartan in diabetic nephropathy: interaction with ACE insertion/deletion genotype?

OBJECTIVE

Several observational follow-up studies have found that the D allele of the insertion (I)/deletion (D) polymorphism of the ACE gene (ACE/ID) is associated with an increased risk of renal function loss, even during ACE inhibition. Therefore, we investigated the long-term effect of the angiotensin II subtype-1 (AT1) receptor antagonist losartan (100 mg o.d.) on kidney function in II and DD type 1 diabetic patients with diabetic nephropathy.

RESEARCH DESIGN AND METHODS

A total of 54 hypertensive type 1 diabetic patients with diabetic nephropathy homozygous for the insertion (n = 26) or the deletion (n = 28) allele were included in the study. After a 4-week washout, the patients received losartan (tablet, 100 mg o.d.) and were followed prospectively with a mean follow-up period of 36 months. Patients and investigators were blinded to ACE genotypes. At baseline, after 2 and 4 months and every 6 months thereafter, glomerular filtration rate (GFR), albuminuria, and 24-h blood pressure were determined.

RESULTS

At baseline, GFR, albuminuria, and blood pressure were similar in the two genotype groups, II versus DD: mean (SD), 86 (22) vs. 88 (24) ml. min(-1). 1.73 m(-2); median (interquartile range), 1,134 (598-2,023) vs. 1,451 (893-1,766) mg/24 h; and mean (SD), 156/82 (17/9) vs. 153/80 (17/11) mmHg, respectively. GFR decreased similarly in both genotype groups, versus DD, respectively (P = 0.4): geometric mean (95% CI), 2.9 (2.0-4.2) vs. 3.4 (2.3-5.1) ml. min(-1). year(-1). Albuminuria and arterial blood pressure were significantly reduced during the study; no differences were noted between groups. During follow-up, albuminuria was decreased by 75% (95% CI 59-85) and 73% (56-83) in the II and DD groups, respectively (P < 0.01 vs. baseline). Mean systolic and diastolic blood pressures were 139/74 mmHg (14/8) in both genotype groups during the study (P < 0.01 vs. baseline).

CONCLUSIONS

In contrast to previous observational studies with ACE inhibitors, long-term treatment with losartan has similar beneficial renoprotective effects on progression of diabetic nephropathy in hypertensive type 1 diabetic patients with ACE II and DD genotypes.

Trends in the prevalence of diabetic nephropathy in type 1 and type 2 diabetes

PURPOSE OF REVIEW

To summarize recent trends in the prevalence of nephropathy due to diabetes and to assess the causes of these changes. Such analysis may influence our strategy to reduce the increasing numbers of cases.

RECENT FINDINGS

Registry data show a progressive increase in the number of cases of nephropathy due to type 2 diabetes such that diabetes is now the leading cause of end-stage renal failure. Despite the increasing incidence of type 1 diabetes, European data indicate the numbers of type 1 patients going on to dialysis are stable. The increase in the prevalence of type 2 diabetes, which in itself is related to increasing levels of obesity, is a major factor but the increase in end-stage renal failure is disproportionately greater. Other factors are therefore important such as earlier development of diabetes and better prevention of coronary events. Similar changes are occurring worldwide. Clinical predictors and genetic markers are being studied.

SUMMARY

More active management of proteinuric type 2 diabetic patients is required to achieve the demanding targets recommended on the basis of clinical trial data. However, the figures suggest that only widespread application of public health measures aimed at the epidemic of type 2 diabetes itself will prevent further rapid escalation of the numbers of type 2 patients reaching end-stage renal failure.