Jan Schulze

Genetic variation in the gene encoding calpain-10 is associated with type 2 diabetes mellitus

Type 2 or non-insulin-dependent diabetes mellitus (NIDDM) is the most common form of diabetes worldwide, affecting approximately 4% of the worlds adult population. It is multifactorial in origin with both genetic and environmental factors contributing to its development. A genome-wide screen for type 2 diabetes genes carried out in Mexican Americans localized a susceptibility gene, designated NIDDM1, to chromosome 2. Here we describe the positional cloning of a gene located in the NIDDM1 region that shows association with type 2 diabetes in Mexican Americans and a Northern European population from the Botnia region of Finland. This putative diabetes-susceptibility gene encodes a ubiquitously expressed member of the calpain-like cysteine protease family, calpain-10 (CAPN10). This finding suggests a novel pathway that may contribute to the development of type 2 diabetes.

Risk factors for myocardial infarction and death in newly detected NIDDM: the Diabetes Intervention Study, 11-year follow-up

Summary The Diabetes Intervention Study (DIS) is a prospective population-based multicentre trial of newly detected cases of non-insulin-dependent diabetes mellitus (NIDDM). This report analyses the risk factors for subsequent coronary heart disease and all-cause death during the 11-year follow-up. The prognostic significance of the categories of the NIDDM Policy Group was validated with respect to the incidence of coronary heart disease and mortality. At baseline 1139 subjects, aged 30–55 years at the time of diabetes detection and classified as diet controlled after a 6-week screening phase, were included. Of the patients 112 (15.2 %) suffered from myocardial infarction, 197 (19.82 %) of 994 had died. The odds ratio for all-cause mortality compared to the general population for males at the age of 36–45 years was 5.1 and for females 7.0. In multivariate analysis age, blood pressure and smoking were independent risk factors for myocardial infarction and male sex, age, blood pressure, triglycerides, postprandial blood glucose and smoking for death, respectively. The categories of the NIDDM Policy Group target parameters for blood glucose, triglycerides and blood pressure were significant predictors of both CHD and death. Thus, it appears that in NIDDM good control of blood glucose, blood pressure and triglycerides is associated with a lower incidence of coronary heart disease and death rate respectively. [Diabetologia (1996) 39: 1577–1583]

Meta-Analysis and a Large Association Study Confirm a Role for Calpain-10 Variation in Type 2 Diabetes Susceptibility

To the Editor: Variation in the calpain-10 gene (CAPN10 [MIM 605286]) was recently linked and associated with type 2 diabetes mellitus (T2DM) susceptibility (Horikawa et al. 2000). The initial linkage of T2DM to chromosome 2 was found in a population of Mexican Americans from Starr County, Texas (Hanis et al. 1996). Specific combinations of three intronic variants, designated “SNP-43,” “SNP-19,” and “SNP-63,” that capture most of the haplotype diversity at CAPN10 were associated with a three-fold increased risk of T2DM in this population and could account for the observed linkage (Horikawa et al. 2000). Subsequent association and linkage studies of these three polymorphisms in other populations have produced conflicting results, with association being observed in some populations (Baier et al. 2000 [Pima Indian]; Cassell et al. 2002 [South Indian]; Garant et al. 2002 [African American]; Malecki et al. 2002 [Polish]; Orho-Melander et al. 2002 [Finnish/Botnia]), but not others (Evans et al. 2001 [British]; Hegele et al. 2001 [Oji-Cree Indians]; Tsai et al. 2001 [Samoan]; Xiang et al. 2001 [Chinese]; Daimon et al. 2002 [Japanese]; Elbein et al. 2002 [whites from Utah]; Fingerlin et al. 2002 [Finnish]; Rasmussen et al. 2002 [Danish and Swedish]; Horikawa et al. 2003 [Japanese]). We previously reported that another variant, SNP-44 (designated “CAPN10-g4841T→C”; minor allele frequency 16%), located in intron 3 and 11 bp from SNP-43, was independently associated with T2DM in whites from the United Kingdom (Evans et al. 2001). Further studies have provided tentative support for a role of SNP-44 in T2DM and related traits: associations with polycystic ovary syndrome (Gonzalez et al. 2002) and with measures of oral glucose tolerance (Wang et al. 2002; Tschritter et al. 2003) have been reported. Functional studies suggest that SNP-44 is located in an enhancer element and might affect CAPN10 expression (Horikawa et al. 2000). Also, in the U.K., German, Japanese, and South Indian populations, SNP-44 is in perfect linkage disequilibrium (r2=1) with a missense mutation Thr504Ala (SNP-110) and two polymorphisms in the 5′-UTR (SNP-134 and SNP-135) (Evans et al. 2001; Cassell et al. 2002; Y. Horikawa and P. E. Schwarz, unpublished data). To assess the association of SNP-44 with T2DM more comprehensively, we performed a meta-analysis of all published SNP-44/T2DM association study data. To identify all relevant published studies, we searched PubMed using the keywords “calpain 10,” “diabetes,” “44,” “SNP 44,” “CAPN10,” and “type 2,” in different combinations. When necessary, authors were contacted to obtain exact genotype numbers, so that precise odds ratios (ORs) from each study could be calculated. Our search identified 10 published case/control studies, consisting of 3,303 subjects. The studies were spread across a number of ethnic groups: British (three studies, Evans et al. 2001); Chinese (Wang et al. 2002); Japanese (Daimon et al. 2002; Horikawa et al. 2003); Finnish/Botnia (two studies, Orho-Melander et al. 2002); South Indian (Cassell et al. 2002); and Mexican American (Horikawa et al. 2000). The frequency of the T2DM-associated SNP-44 C allele (allele 2) ranged from 6% in Mexican Americans to 25% in the Botnia I control population. There was no evidence for OR heterogeneity (Q test P=.27), and, although these studies are only a small sample from the many existing T2DM genetic resources, a funnel-plot analysis (Egger et al. 1997) suggested an absence of publication bias (P=.44). A Mantel-Haenszel meta-analysis of these studies showed that the C allele was associated with increased risk of T2DM (OR 1.17 [1.02–1.34], P=.02). Three transmission/disequilibrium tests (TDT) had been performed (Evans et al. 2001; Cassell et al. 2002; Orho-Melander et al. 2002). The combined TDT results demonstrated that the C allele was significantly overtransmitted (117 transmitted vs. 77 not transmitted, P=.004) from heterozygous parents to diabetic offspring. Although this result cannot be considered independent replication, as proband data was included in the case/control meta-analysis from two of the TDT studies (Evans et al. 2001; Cassell et al. 2002), it provides evidence that the association is not due to population stratification. Of the 10 studies in the meta-analysis, only 1 reported a significant (P<.05) association (Evans et al. 2001). However, these studies were small and the mean power to detect an OR of 1.17 at P<.05 was ∼11% (range 5%–14%). In the context of genetic association studies, which test many polymorphisms in numerous candidate genes, a P value of .02 can only be considered evidence suggestive of a real association. We therefore genotyped SNP-44 in an additional 4,213 subjects: 3,274 white European subjects from four case/control studies (one British, two German, and one Czech); 691 Japanese subjects from two case/control studies; and 248 Mexican (mestizo) subjects from Mexico City and Orizaba City from one case/control study. Overall, this provided 2,056 subjects with T2DM and 2,157 controls, and a power of ∼80% to detect an OR of 1.17. Clinical details of the study subjects are presented in table 1; further details are available as supplementary information from the authors. All studies were approved by the relevant ethics committee, and all subjects gave their informed consent. Table 1 Clinical Characteristics of Subjects in Study[Note] When all the studies were combined, there was no evidence for between-studies OR heterogeneity (Q test P=.23); a Mantel-Haenszel fixed-effects model was therefore used for subsequent analysis. Meta-analysis of the new studies gave an OR for the SNP-44 C allele of 1.18 (1.04–1.34), P=.01 (fig. 1). A combined meta-analysis of all previously published data and our new data gave an OR of 1.17 (1.07–1.29), P=.0007. All study populations were in Hardy-Weinberg equilibrium except the T2DM cohort of Horikawa et al. 2003 (P=.005) and the control population of the third Japanese study (P=.02). Although these deviations may be due to random fluctuation and multiple-hypothesis testing, they contributed a large amount to heterogeneity (27% of the Q statistic); excluding these studies, the SNP-44 C allele OR for the new studies was 1.23 (1.07–1.40), P=.003; the overall OR was 1.19 (1.08–1.31), P=.0005. This OR is of similar magnitude to that of E23K (Gloyn et al. 2003; Love-Gregory et al. 2003; Nielsen et al. 2003) and Pro12Ala (Altshuler et al. 2000), the other common variants confirmed as T2DM-susceptibility polymorphisms. An OR of 1.17 is low and may help explain why there is little evidence for linkage of the CAPN10 region to T2DM in most populations. The haplotypes responsible for the CAPN10 linkage seen in the Mexican American population were associated with a higher T2DM OR (∼3.0) and were more likely to be detected by linkage analysis (Horikawa et al. 2000). These haplotypes are less common in other populations. Figure 1 Mantel-Haenszel OR meta-analysis plot (fixed effects) for SNP-44 association with T2DM. Point estimates and 95% CLs for each previously published, new, and combined case/control study. SNP-44 is in perfect linkage disequilibrium (r2=1) with the missense mutation, Thr504Ala, and two SNPs (SNP-134 and SNP-135) in the 5′-UTR and therefore may not be the causal variant. Further haplotype and functional analyses are required to confirm which of these polymorphisms contribute to T2DM susceptibility. In conclusion, our results have confirmed that a CAPN10 haplotype defined by the SNP-44 polymorphism predisposes to T2DM. Meta-analyses of published genetic associations, combined with large replication studies, are a powerful approach to detecting susceptibility variants in common disease.

Diabetes Intervention Study Multi-Intervention Trial in Newly Diagnosed NIDDM

Objective In a randomized 5-yr multi-intervention trial, we tested the efficacy of intensified health education (IHE) in improving metabolic control and reducing the level of coronary risk factors and incidence of ischemic heart disease (IHD). Research Design and Methods Within the intervention group, the benefit of clofibric acid was evaluated in a double-blind study. One thousand one hundred thirty-nine newly diagnosed middle-aged (30- to 55-yr-old) patients with non-insulindependent diabetes mellitus (NIDDM) entered the study. They were classified as diet controlled after a 6- wk screening phase with conventional dietary treatment. During the follow-up, the control group (n = 378) was cared for at different diabetes outpatient clinics with a standardized surveillance. The intervention group (n = 761) had a structured IHE that included dietary advice, antismoking and antialcohol education, and ways to enhance physical activity. Results Randomly, 379 of the IHE patients received 1.6 g clofibric acid/day, and the others received placebo. IHE resulted in improved glucose control (adjusted fasting blood glucose) levels after 5 yr (control subjects 9.27 mM, IHE group 8.71 mM, and IHE plus clofibric acid group 8.60 mM, P < 0.01). The better glycemic control was achieved with fewer antidiabetic drugs. After 5 yr, antidiabetic drugs were prescribed to 47% of the control subjects, 28% of the IHE group, and 34% of the IHE plus clofibric acid group (cutoff limit for drug application was postprandial blood glucose of ≥13.87 mM). The ratio of polyunsaturated to saturated fatty acids (0.26 vs. 0.40, P < 0.01) and physical activity (174 vs. 327 scores, P < 0.01) were increased, and blood pressure, tobacco, and alcohol consumption were significantly reduced by IHE. However, IHE had no effect on calorie intake, percentage of fat in the diet (45%), and body weight. The most important finding was the significant increase of blood cholesterol in all three groups (+ 0.47, +0.36, and +0.34 mM, respectively). Clofibric acid only prevented the increase of triglyceride levels (+ 0.56, +0.24, and +0.05 mM, respectively). The incidence rate per 1000 for myocardial infarction was 30.3 for control subjects, 53.6 for the IHE group, and 55.6 for the IHE plus clofibric acid group. The corresponding rates for IHD incidence were 90.9, 97.8, and 98.8, respectively. Men suffered more frequently from myocardial infarction, whereas women developed ECG criteria for IHD more frequently. Among the 35 cases of death, besides cardiovascular diseases, liver cirrhosis and neoplasia were the predominant causes. The death rate per 1000 in control subjects was 46.2, 30.6 in the IHE group, and 27 among patients with IHE plus clofibric acid. Conclusions IHE was of substantial benefit for the control of glycemia, significantly diminished the need for antidiabetic drugs, and reduced a cluster of risk factors but had no effect on the control of blood lipids. This could be one major reason for the failure of IHE, effective lowering of blood pressure, and clofibric acid to prevent cardiovascular complications. Clofibric acid was only effective in reducing triglycerides.

Therapeutic Potentials of Acarbose as First-Line Drug in NIDDM Insufficiently Treated With Diet Alone

Objecative Acarbose inhibits α-glucosidases of the small intestine and thus delays glucose release from complex carbohydrates. Therefore, its efficacy and acceptability as a first-line drug in non-insulin-dependent diabetes mellitus (NIDDM) insufficiently treated with diet alone was tested in a randomized double-blind placebo-controlled study. Research Design And Methods Ninety-four NIDDM subjects, aged 43–70 yr with average body mass index of 28 kg/m2 and undergoing a pretreatment period of at least 3 mo with diet alone, were treated with 100 mg acarbose three times daily or placebo for 24 wk. The patients were recruited after a 4-wk screening period of dietary reinforcement. The inclusion limits for patients termed diet not satisfactory were fasting blood glucose (FBG) ≥ 7.8 mM and/or postprandial blood glucose (BG) ≥ 10 mM. Results FBG was lowered in the acarbose group from 9.8 to 8.4 mM and in the placebo group from 10.2 to 9.6 mM after 24 wk (P = 0.007 vs. placebo). The most impressive therapeutic effect was a highly significant reduction of postprandial hyperglycemia for at least 5 h after the test meal (1-h postprandial BG with acarbose 10.4 mM and placebo 13.5 mM at 24 wk, P < 0.001) accompanied by a significant decrease in HbA1 (acarbose 8.65%, placebo 9.32%, P = 0.003). Whereas C-peptide and fasting serum insulin were not significantly affected by acarbose, postprandial insulin increment was ∼ 30% lower after 24 wk compared with placebo. Furthermore, acarbose significantly reduced 1-h postprandial triglyceride levels. After an initial phase of > 4 wk (when 76.6% in the acarbose group vs. 28% on placebo complained about flatulence, P < 0.001), the drug was well accepted. At the end of the study, only 32% showed mild or moderate gastrointestinal sensations. Conclusions Extrapolation shows that acarbose is an efficient and acceptable drug for the treatment of NIDDM with poor metabolic control by diet alone. It has beneficial effects on postprandial hyperinsulinemia and postprandial hypertriglyceridemia.

Mutations in the Hepatocyte Nuclear Factor-1α Gene in MODY and Early-Onset NIDDM: Evidence for a Mutational Hotspot in Exon 4

We have recently shown that mutations in the gene encoding the transcription factor hepatocyte nuclear factor (HNF)-1α are the cause of one form of maturity-onset diabetes of the young (MODY3). Here, we report the exon-intron organization and partial sequence of the human HNF-1α gene. In addition, we have screened the ten exons and flanking introns of this gene for mutations in a group of 25 unrelated white subjects from Germany who presented with NIDDM before 35 years of age and had a first-degree relative with NIDDM. Mutations were identified in nine of these individuals, suggesting that mutations in the HNF-1α gene are a common cause of diabetes in German subjects with early-onset NIDDM and a family history of diabetes. Thus, screening for mutations in this gene may be indicated in subjects with early-onset NIDDM. Interestingly, three of the nine mutations occurred at the same site in exon 4 with insertion of a C in a polyCtract, centered around codon 290 (designated Pro291fsinsC), thereby resulting in a frameshift during translation and premature termination. Analyses of linked DNA polymorphisms in the HNF-1α gene indicated that the Pro291fsinsC mutation was present on a different haplotype in each subject, implying that the polyC tract represents a mutational hot spot. We have also identified the mutation in the HNF-1α gene in the Jutland pedigree, one of the original MODY pedigrees reported in the literature, as being a T→G substitution in codon 241, resulting in the replacement of a conserved Cys by Gly (C241G). The information on the sequence of the HNF-1α gene and its promoter region will facilitate the search for mutations in other subjects and studies of the role of the gene in determining normal β-cell function.

Evaluation of a Diabetes Management System Based on Practice Guidelines, Integrated Care, and Continuous Quality Management in a Federal State of Germany : A population-based approach to health care research

OBJECTIVE—The aim of this study was to evaluate the Saxon Diabetes Management Program (SDMP), which is based on integrated practice guidelines, shared care, and integrated quality management. The SDMP was implemented into diabetes contracts between health insurance providers, general practitioners (GPs), and diabetes specialized practitioners (DSPs) unified in the Saxon association of Statutory Health Insurance Physicians. RESEARCH DESIGN AND METHODS—The evaluation of the SDMP in Germany represents a real-world study by using clinical data collected from participating physicians. Between 2000 and 2002 all DSPs and about 75% of the GPs in Saxony participated. Finally, 291,771 patients were included in the SDMP. Cross-sectional data were evaluated at the beginning of 2000 (group A1) and at the end of 2002 (group A2). A subcohort of 105,204 patients was followed over a period of 3 years (group B). RESULTS—The statewide implementation of the SDMP resulted in a change in therapeutic practice and in better cooperation. The median A1C at the time of referral to DSPs decreased from 8.5 to 7.5%, and so did the overall mean. At the end, 78 and 61% of group B achieved the targets for A1C and blood pressure, respectively, recommended by the guidelines compared with 69 and 50% at baseline. Patients with poorly controlled diabetes benefited the most. Preexisting regional differences were aligned. CONCLUSIONS—Integrated care disease management with practicable integrated quality management including collaboration between GPs and specialist services is a significant innovation in chronic care management and an efficient way to improve diabetes care continuously.

The Finnish Diabetes Risk Score Is Associated with Insulin Resistance and Progression towards Type 2 Diabetes

OBJECTIVE The Finnish Diabetes Risk Score (FINDRISC) questionnaire is a practical screening tool to estimate the diabetes risk and the probability of asymptomatic type 2 diabetes. In this study we evaluated the usefulness of the FINDRISC to predict insulin resistance in a population at increased diabetes risk. DESIGN Data of 771 and 526 participants in a cross-sectional survey (1996) and a cohort study (1997-2000), respectively, were used for the analysis. Data on the FINDRISC and oral glucose tolerance test parameters were available from each participant. The predictive value of the FINDRISC was cross-sectionally evaluated using the area under the curve-receiver operating characteristics method and by correlation analyses. A validation of the cross-sectional results was performed on the prospective data from the cohort study. RESULTS The FINDRISC was significantly correlated with markers of insulin resistance. The receiver operating characteristics-area under the curve for the prediction of a homeostasis model assessment insulin resistance index of more than five was 0.78 in the cross-sectional survey and 0.74 at baseline of the cohort study. Moreover, the FINDRISC at baseline was significantly associated with disease evolution (P < 0.01), which was defined as the change of glucose tolerance during the 3 yr follow-up. CONCLUSIONS The results indicate that the FINDRISC can be applied to detect insulin resistance in a population at high risk for type 2 diabetes and predict future impairment of glucose tolerance.

Hepatic function in a family with a nonsense mutation (R154X) in the hepatocyte nuclear factor-4alpha/MODY1 gene.

Maturity-onset diabetes of the young (MODY) is a genetically heterogeneous monogenic disorder characterized by autosomal dominant inheritance, onset usually before 25 yr of age, and abnormal pancreatic beta-cell function. Mutations in the hepatocyte nuclear factor(HNF)-4alpha/MODY1, glucokinase/MODY2, and HNF-1alpha/MODY3 genes can cause this form of diabetes. In contrast to the glucokinase and HNF-1alpha genes, mutations in the HNF-4alpha gene are a relatively uncommon cause of MODY, and our understanding of the MODY1 form of diabetes is based on studies of only a single family, the R-W pedigree. Here we report the identification of a second family with MODY1 and the first in which there has been a detailed characterization of hepatic function. The affected members of this family, Dresden-11, have inherited a nonsense mutation, R154X, in the HNF-4alpha gene, and are predicted to have reduced levels of this transcription factor in the tissues in which it is expressed, including pancreatic islets, liver, kidney, and intestine. Subjects with the R154X mutation exhibited a diminished insulin secretory response to oral glucose. HNF-4alpha plays a central role in tissue-specific regulation of gene expression in the liver, including the control of synthesis of proteins involved in cholesterol and lipoprotein metabolism and the coagulation cascade. Subjects with the R154X mutation, however, showed no abnormalities in lipid metabolism or coagulation except for a paradoxical 3.3-fold increase in serum lipoprotein(a) levels, nor was there any evidence of renal dysfunction in these subjects. The results suggest that MODY1 is primarily a disorder of beta-cell function.

Efficacy of α‐glucosidase inhibitors on lipids in NIDDM subjects with moderate hyperlipidaemia

This paper summarizes literature data concerning the action of acarbose, an α‐glucosidase inhibitor, on the concentrations of plasma lipids. Clinical trials in which acarbose has been used in the treatment of non‐insulin‐dependent diabetics have sometimes shown that it reduces serum triglycerides while it has little or no effect on serum cholesterol levels. The results of a randomized double‐blind placebo‐controlled study lasting 24 weeks are discussed in more detail. Under the controlled conditions, the effects of acarbose treatment on fasting concentrations of cholesterol, HDL‐cholesterol, and triglycerides did not reach statistical significance for the entire patient group. However, in the highest tertile of initial cholesterol concentrations acarbose treatment led to significant lowering of the cholesterol concentration and of the total‐to‐HDL‐cholesterol ratio. The most important benefits of acarbose were observed after a test meal given on day 0 and on week 24 of treatment. The triglyceride increment 1 h postprandial was significantly lowered. This was associated by a significant decrease of the insulin increment. Reduction of hyperinsulinaemia appears to be the mechanism by which acarbose treatment can improve plasma lipid concentrations.