Genetic susceptibility to non-insulin dependent diabetes mellitus and glucose intolerance are located in HLA region

Effect of Immunomodulating Extract and Some Isolates from Etlingera rubroloba A.D. Poulsen Fruits on Diabetic Patients with Tuberculosis

Diabetes mellitus (DM) is a disease easily complicated by tuberculosis (TB) due to impaired function of the innate immune response. The successes of the discovery of immunomodulatory compounds needs to be continued to introduce new insights into the innate immune response. In previous studies, plant compounds of Etlingera rubroloba A.D. Poulsen (E.rubroloba) were demonstrated to have potential as an immunomodulators. This study aims to isolate and identify the structure of the compounds of E.rubroloba fruit that could effectively improve the function of the innate immune response in individuals with DM infected with TB. The isolation and purification of the compounds of the E.rubroloba extract were carried out by radial chromatography (RC) and thin-layer chromatography (TLC). Identification of the isolated compound structures was determined by measuring the proton (¹H) and carbon (¹³C) nuclear magnetic resonance (NMR). In vitro testing was performed on the immunomodulating activity of the extracts and isolated compounds on DM model macrophages infected with TB antigens. This study succeeded at isolating and identifying the structures of two isolate compounds, namely Sinaphyl alcohol diacetat (BER-1), and Ergosterol peroxide (BER-6). The two isolates were more effective as immunomodulators than the positive controls were, which differed significantly (* p < 0.05) at the reducing interleukin-12 (IL-12) levels and Toll-like receptor-2 (TLR-2) protein expression and increasing the human leucocyte antigen-DR (HLA-DR) protein expression in DM infected with TB. The isolated compound was discovered in E. rubroloba fruits, which has been reported to have the potential to be developed as an immunomodulatory agent. Follow-up testing to determine the mechanism and effectiveness of these compounds as immunomodulators for DM patients is required so that they are not susceptible to TB infection.

Class I MHC Polymorphisms Associated with Type 2 Diabetes in the Mexican Population

Type 2 diabetes (T2D) has been linked to the expression of Human Leukocyte Antigens, principally to the Major Histocompatibility Complex Class II, with only scarce reports of Major Histocompatibility Complex Class I in specific populations. The objective of the present work was to explore the presence of polymorphisms in the MHC Class I related to T2D in the Mexican population using the Genome-Wide Association Studies Slim Initiative in Genomic Medicine of the Americas (GWAS SIGMA) database. This database contains information on 3848 Mexican individuals with T2D and 4366 control individuals from the same population without a clinical or hereditary history of the disease. The searching criteria considered a p-value of <0.005 and an odds ratio (OR) of >1.0. Ten novel, statistically significant nucleotide variants were identified: four polymorphisms associated with HLA-A (A*03:01:01:01) and six with HLA-C (C*01:02:01:01). These alleles have a high prevalence in Latin American populations and could potentially be associated with autoimmunity mechanisms related to the development of T2D complications.

Untangling the genetic link between type 1 and type 2 diabetes using functional genomics

There is evidence pointing towards shared etiological features between type 1 diabetes (T1D) and type 2 diabetes (T2D) despite both phenotypes being considered genetically distinct. However, the existence of shared genetic features for T1D and T2D remains complex and poorly defined. To better understand the link between T1D and T2D, we employed an integrated functional genomics approach involving extensive chromatin interaction data (Hi-C) and expression quantitative trait loci (eQTL) data to characterize the tissue-specific impacts of single nucleotide polymorphisms associated with T1D and T2D. We identified 195 pleiotropic genes that are modulated by tissue-specific spatial eQTLs associated with both T1D and T2D. The pleiotropic genes are enriched in inflammatory and metabolic pathways that include mitogen-activated protein kinase activity, pertussis toxin signaling, and the Parkinson's disease pathway. We identified 8 regulatory elements within the TCF7L2 locus that modulate transcript levels of genes involved in immune regulation as well as genes important in the etiology of T2D. Despite the observed gene and pathway overlaps, there was no significant genetic correlation between variant effects on T1D and T2D risk using European ancestral summary data. Collectively, our findings support the hypothesis that T1D and T2D specific genetic variants act through genetic regulatory mechanisms to alter the regulation of common genes, and genes that co-locate in biological pathways, to mediate pleiotropic effects on disease development. Crucially, a high risk genetic profile for T1D alters biological pathways that increase the risk of developing both T1D and T2D. The same is not true for genetic profiles that increase the risk of developing T2D. The conversion of information on genetic susceptibility to the protein pathways that are altered provides an important resource for repurposing or designing novel therapies for the management of diabetes.

HLA Class II Allele Analyses Implicate Common Genetic Components in Type 1 and Non-Insulin-Treated Type 2 Diabetes

CONTEXT

Common genetic susceptibility may underlie the frequently observed co-occurrence of type 1 and type 2 diabetes in families. Given the role of HLA class II genes in the pathophysiology of type 1 diabetes, the aim of the present study was to test the association of high density imputed human leukocyte antigen (HLA) genotypes with type 2 diabetes.

OBJECTIVES AND DESIGN

Three cohorts (Ntotal = 10 413) from Leipzig, Germany were included in this study: LIFE-Adult (N = 4649), LIFE-Heart (N = 4815) and the Sorbs (N = 949) cohort. Detailed metabolic phenotyping and genome-wide single nucleotide polymorphism (SNP) data were available for all subjects. Using 1000 Genome imputation data, HLA genotypes were imputed on 4-digit level and association tests for type 2 diabetes, and related metabolic traits were conducted.

RESULTS

In a meta-analysis including all 3 cohorts, the absence of HLA-DRB5 was associated with increased risk of type 2 diabetes (P = 0.001). In contrast, HLA-DQB*06:02 and HLA-DQA*01:02 had a protective effect on type 2 diabetes (P = 0.005 and 0.003, respectively). Both alleles are part of the well-established type 1 diabetes protective haplotype DRB1*15:01~DQA1*01:02~DQB1*06:02, which was also associated with reduced risk of type 2 diabetes (OR 0.84; P = 0.005). On the contrary, the DRB1*07:01~DQA1*02:01~DQB1*03:03 was identified as a risk haplotype in non-insulin-treated diabetes (OR 1.37; P = 0.002).

CONCLUSIONS

Genetic variation in the HLA class II locus exerts risk and protective effects on non-insulin-treated type 2 diabetes. Our data suggest that the genetic architecture of type 1 diabetes and type 2 diabetes might share common components on the HLA class II locus.

Genome-wide association study identifies novel risk variants from RPS6KA1, CADPS, VARS, and DHX58 for fasting plasma glucose in Arab population

Consanguineous populations of the Arabian Peninsula, which has seen an uncontrolled rise in type 2 diabetes incidence, are underrepresented in global studies on diabetes genetics. We performed a genome-wide association study on the quantitative trait of fasting plasma glucose (FPG) in unrelated Arab individuals from Kuwait (discovery-cohort:n = 1,353; replication-cohort:n = 1,196). Genome-wide genotyping in discovery phase was performed for 632,375 markers from Illumina HumanOmniExpress Beadchip; and top-associating markers were replicated using candidate genotyping. Genetic models based on additive and recessive transmission modes were used in statistical tests for associations in discovery phase, replication phase, and meta-analysis that combines data from both the phases. A genome-wide significant association with high FPG was found at rs1002487 (RPS6KA1) (p-discovery = 1.64E-08, p-replication = 3.71E-04, p-combined = 5.72E-11; β-discovery = 8.315; β-replication = 3.442; β-combined = 6.551). Further, three suggestive associations (p-values < 8.2E-06) with high FPG were observed at rs487321 (CADPS), rs707927 (VARS and 2Kb upstream of VWA7), and rs12600570 (DHX58); the first two markers reached genome-wide significance in the combined analysis (p-combined = 1.83E-12 and 3.07E-09, respectively). Significant interactions of diabetes traits (serum triglycerides, FPG, and glycated hemoglobin) with homeostatic model assessment of insulin resistance were identified for genotypes heterozygous or homozygous for the risk allele. Literature reports support the involvement of these gene loci in type 2 diabetes etiology.

Double or hybrid diabetes: A systematic review on disease prevalence, characteristics and risk factors

Diabetes mellitus is a worldwide epidemic affecting the health of millions of people. While type 1 diabetes (T1D) is caused by autoimmune destruction of the insulin-producing beta cells of the pancreas, type 2 diabetes (T2D) results from a combination of insulin resistance and beta cell insulin secretory defect. Clear definition and diagnosis of these two types of diabetes has been increasing more and more difficult, leading to the inclusion of a new category, namely double or hybrid diabetes (DD) that demonstrates symptoms of both T1D and T2D via the accelerator hypothesis. In this review, we discuss the worldwide prevalence of DD, its main physiological characteristics, including beta-cell autoimmunity, insulin resistance, and cardiovascular disease, the main risk factors of developing DD, mainly genetics, obesity and lifestyle choices, as well as potential treatments, such as insulin titration, metformin and behavioural modifications. Increasing awareness of DD among the general population and primary care practitioners is necessary for successfully treating this complex, hybrid disease in the future.

The emerging global epidemic of type 1 diabetes

Type 1 diabetes mellitus (T1D) can occur at any age, with a peak in incidence around puberty. Classification between T1D and type 2 diabetes becomes more challenging with increasing age of onset of T1D over time develops in genetically predisposed individuals. The main susceptibility is conferred with human leukocyte antigen (HLA) genes. Some of the geographic variation in incidence and familial aggregation is explained by differences in HLA haplotypes. In many populations, the incidence is somewhat higher in males than in females, and a 1.3- to 2.0-fold male excess in incidence after about 15 years of age exists in most populations. The incidence of childhood-onset T1D varies markedly among countries. East Asian and native American populations have low incidences (approximately 0.1-8 per 100 000/year), while the highest rates are found in Finland (>60 per 100 000/year), Sardinia (40 per 100 000/year), and Sweden (47 per 100 000/year). The risk is highest in European-derived populations. About 10 %-20 % of newly diagnosed childhood cases of T1D have an affected first-degree relative. Those with an affected sibling or parent have a cumulative risk of 3 %-7 % up to about 20 years of age, as compared with <1 % in the general population. The cumulative incidence among the monozygotic co-twins of persons with T1D is less than 50 %. Thus, the majority of genetically predisposed people do not develop T1D. Studies assessing temporal trends have shown that the incidence of childhood-onset T1D has increased in all parts of the world. The average relative increase is 3 %-4 % per calendar year. For instance, in Finland, the incidence today is 5 times higher than 60 years ago. At the same time, the age at onset of T1D in children has become younger. It is strongly believed that nongenetic factors are important for the development of T1D and its increase, but the causative evidence is missing. The causes for this increasing trend and current epidemic still remain unknown.

The convergence of type 1 and type 2 diabetes in childhood: the accelerator hypothesis

It seems likely that type 1 and type 2 diabetes lie at different points of the same spectrum, separated by the misunderstanding that one belongs to childhood and the other to adulthood. The spectrum is that of tempo--the rate at which beta cell function is lost over time. A combination of beta cell up-regulation (insulin demand, largely determined by obesity) and the genetically-determined immune response to it ('autoimmunity') determines tempo, ranging from slow to fast with every variant in between. There is good evidence that people who go on to develop type 1 (fast) diabetes are, like those who develop type 2 (slow diabetes), insulin resistant, and overwhelming evidence that body mass plays a key role. The prevention of type 1 diabetes may lie in weight restriction from an early age.

The imbalance of Th17/Th1/Tregs in patients with type 2 diabetes: relationship with metabolic factors and complications

Immune disorders are linked to the development of type 2 diabetes (T2D) and its complications. The relationship of CD4(+)CD25(hi) T regulatory cells (Treg) and pro-inflammatory Th17 and Th1 subsets in T2D patients with metabolic disorders and complications need to be determined. The ratios of CD4(+)CD25(hi) Treg/Th17 cells and CD4(+)CD25(hi) Treg/Th1 cells, but not Th17/Th1 cells, were significantly decreased in T2D patients. The thymic output CD4(+)Foxp3(+)Helios(+) Tregs were normal but peripheral induced CD4(+)Foxp3(+)Helios(-) Tregs were decreased in T2D patients. The Bcl-2/Bax ratio decreased in CD4(+)CD25(hi) Tregs in T2D patients, supporting the increased sensitivity to cell death of these cells in T2D. CD4(+)CD25(hi)CD127(-) Tregs in T2D patients with microvascular complications were significantly less than T2D patients with macrovascular complications. Importantly, CD4(+)CD25(hi)CD127(-) Tregs were positively correlated with plasma IL-6, whereas IL-17(+)CD4(+)cells were negatively related to high-density lipoprotein (HDL). Our data offered evidence for the skewed balance of anti- and pro-inflammatory T cell subsets in T2D patients and identified that HDL closely modulate T cell polarization. These results opened an alternative explanation for the substantial activation of immune cells as well as the development of T2D and complications, which may have significant impacts on the prevention and treatment of T2D patients.

No association of the SUMO4 polymorphism M55V variant in type 2 diabetes in Iranian subjects

INTRODUCTION

Diabetes mellitus incidence has an increasing rate and it's genetic aspect is an important approach as a risk factor and predictive value in this disorder. In some population, SUMO4, a regulator of NF-κB, gene polymorphism is associated with diabetes. A single-nucleotide polymorphism was detected in SUMO4; substituting a highly conserved methionine with a valine residue (M55V). We studied the association between M55V polymorphism in the SUMO4 gene insusceptibility of type 2 diabetes in patients with type 2 diabetes.

MATERIALS AND METHODS

Participants were 50 patients with type 2 diabetes and 50 control Iranian subjects. Genotyping was done using polymorphism chain reaction (PCR) technique and subsequent cleavage by restriction endonuclease (RFLP) for the M55V SUMO4 gene variant.

RESULTS

The frequency of SUMO4 AA, AG and GG were 13%, 25% and 12% in control group and 20%, 22%, 18% in the type 2 diabetes patients respectively. The SUMO4 M55V variant was not associated with the susceptibility of type 2 diabetes.

CONCLUSION

The study indicates that the SUMO4 gene M55V variant was not associated with the susceptibility of the type 2 diabetes polymorphism.

Immunogenetic susceptibility to diabetes mellitus in patients with liver disease

BACKGROUND/AIM

Genetic, environmental, metabolic and infectious influences, such as hepatitis C virus (HCV) infection, are thought to impact on the development of diabetes in patients with liver disease. As specific human leucocyte antigen (HLA) alleles provide the major genetic risk factors for type 1 diabetes, our aim was to investigate whether HLA class I and II alleles constitute additional risk factors for diabetes in patients with liver disease.

METHODS

We evaluated two independent databases of 193 and 728 adult patients with chronic liver disease for the diagnosis of diabetes and the presence of specific HLA subtypes.

RESULTS

In each database, 24 and 19% of patients met criteria for diabetes. In the first database, specific class I and II alleles were observed more frequently in diabetics compared with non-diabetics: Cw7 (50 vs. 32%, P=0.04), DR51 (17 vs. 3%P=0.003) and DQ6 (37 vs. 18%, P=0.02). In the second database, DQ6 was observed in 16% of diabetics vs. 8% of non-diabetics (P=0.04). The DR2-DR51-DQ6 haplotype was higher in patients with diabetes in both databases (22 vs.7%, P=0.02 and 12 vs. 5%, P=0.02). In a subgroup analysis of patients with HCV infection, increased frequencies of Cw7, DR2/DR51, DQ6 and DR2-DR51-DQ6 were also observed to be higher in subjects with diabetes compared with those without diabetes.

CONCLUSIONS

Patients with chronic liver disease, especially those with HCV infection, have an immunogenetic risk for diabetes characterized by the presence of Cw7, DR51, DQ6 and DR2-DR51-DQ6.

Changing perspectives in diabetes: their impact on its classification

Type 1 and type 2 diabetes are usually regarded as distinct disorders, but the convergence of their phenotypes over recent years, the relationship of body weight to the risk of type 1 diabetes, the diminishing importance of the type 1 susceptibility genes and the finding of autoantibodies in patients with type 2 diabetes, invite a different interpretation. The possibility that type 1 and type 2 diabetes, rather than being different, are merely poles of a single spectrum, where variation in the tempo of beta cell loss determines age at onset and symptoms at presentation, has important implications. Correct classification is crucial because it directs appropriate treatment and, where available, prevention. This article argues that type 1 diabetes is currently misclassified, provides evidence that insulin resistance drives type 1 diabetes as it does type 2, and proposes how the 'accelerator hypothesis' can be tested in a randomised controlled trial, which could demonstrate, for the first time, the safe and effective prevention of type 1 diabetes.

A high incidence of type 1 diabetes and an alarming increase in the incidence of type 2 diabetes among young adults in Finland between 1992 and 1996

AIMS/HYPOTHESIS

The aim of this study was to examine the incidence and trends of type 1 and type 2 diabetes in the 15-39 year-old population between 1992 and 1996 in Finland.

SUBJECTS AND METHODS

Data on the nationwide incidence of diabetes were obtained from four data sources: standardised reports from diabetes nurses, the Finnish National Hospital Discharge Register, the Drug Reimbursement Register and the Drug Prescription Register. The inclusion criterion was consistency in the diagnosis of diabetes across at least two data sources. The sex- and age-specific incidence was calculated for 5-year age groups, both for type 1 and type 2 diabetes. The effects of age, sex and year of diagnosis were assessed by fitting the linear regression model to the incidence data.

RESULTS

Between 1992 and 1996 the age-adjusted incidence of type 1 diabetes among 15-39 year olds was 15.9 per 100,000/year. The incidence was highest among the 15-19 year olds and decreased with age. Conversely, the incidence of type 2 diabetes was very low among 15-19 year olds and increased with age. The total age-adjusted incidence of type 2 diabetes among 15-39 year olds was 11.8 per 100,000/year. The average annual increase in the incidence of type 2 diabetes was 7.9% (95% CI 3.7-12.2%).

CONCLUSIONS/INTERPRETATION

The age at which the Finnish population is at risk of type 1 diabetes extends into young adulthood. The rapid increase in the incidence of type 2 diabetes in the young adult population is a current public health problem.

Association of small ubiquitin-like modifier 4 (SUMO4) variant, located in IDDM5 locus, with type 2 diabetes in the Japanese population

CONTEXT

Despite distinct differences in the pathogenesis, epidemiological data have indicated familial clustering of type 1 and type 2 diabetes, suggesting a common genetic basis between these two types of diabetes. Few shared susceptibility genes, however, have been reported to date.

OBJECTIVE

Small ubiquitin-like modifier 4 (SUMO4) has been identified as a candidate gene for the IDDM5 locus and suggested to have possible involvement in immune responses, such as autoimmunity and inflammation. Recent reports demonstrated that a polymorphism with an amino acid substitution (Met55Val) in SUMO4 was associated with type 1 diabetes in Asian populations, although no association was reproduced in subjects of Caucasian descent. The present study aimed to clarify the contribution of SUMO4 to type 2 diabetes susceptibility in the Japanese population.

SUBJECTS

The 753 subjects included 355 cases and 398 control subjects.

METHODS

The SUMO4 Met55Val (rs237025) and 001Msp (rs577001) polymorphisms were genotyped.

RESULTS

Strong linkage disequilibrium (D': 1.0 in each pair of single-nucleotide polymorphisms) across the MAP3K7IP2/SUMO4 region was shown in the Japanese population. The frequency of genotypes with the G allele of the SUMO4 Met55Val polymorphism was significantly higher in patients with type 2 diabetes [odds ratio, 1.46; 95% confidence interval (CI), 1.08-1.93; P = 0.01, chi(2) test]. The association was concentrated in patients without insulin therapy (odds ratio, 1.56; 95% CI, 1.13-2.15; P = 0.0072), but not in those with insulin (odds ratio, 1.24; 95% CI, 0.81-1.89; not significant).

CONCLUSIONS

These data, together with previous reports, suggest the contribution of the SUMO4 Met55Val polymorphism to both type 1 and type 2 diabetes susceptibility in the Japanese population.

HLA-DRB1*08 allele may help to distinguish between type 1 diabetes mellitus and type 2 diabetes mellitus in Mexican children

BACKGROUND

It may be difficult to distinguish type 1 diabetes mellitus (T1DM) from type 2 diabetes mellitus (T2DM) in the pediatric population. Autoantibodies may help to differentiate both types of diabetes, but sometimes these are positive in patients with T2DM and negative in patients with T1DM. The human leukocyte antigen (HLA)-DR genotype has been associated with T1DM and with T2DM only in adults and in determined cases.

AIM

To determine the differences in HLA class II allele frequencies in Mexican children with T1DM and T2DM.

METHODS

We included 72 children with T1DM, 28 children with T2DM, and 99 healthy controls. All were Mexican, and diabetes was diagnosed according to the clinical and laboratory criteria established by the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. The HLA-DRB1 typing was performed using polymerase chain reaction-sequence-specific oligonucleotide probe and polymerase chain reaction sequence-specific primers.

RESULTS

We found an increased frequency of HLA-DRB1*08 and a decreased frequency of HLA-DRB1*04 in the group with T2DM vs. T1DM [p = 0.0001, odds ratio (OR) = 10.58, 95% confidence interval (CI) = 3-40.8 and p = 0.0006, OR = 0.24, 95% CI = 0.11-0.53, respectively]. No significant differences were found between HLA-DRB1 alleles in T2DM vs. controls. In the group with T1DM, there was a significantly increased frequency of the HLA-DR4 and HLA-DR3 alleles relative to controls (p = 0.0000001, OR = 3.59, 95% CI = 2.2-5.8 and p = 0.00009, OR = 4.66, 95% CI = 2.1-10.3, respectively).

CONCLUSION

There are significant differences in the HLA profile in Mexican children with T1DM and T2DM. HLA typing could play a role in the differentiation between both types of diabetes in this population.

Screening of 134 single nucleotide polymorphisms (SNPs) previously associated with type 2 diabetes replicates association with 12 SNPs in nine genes

More than 120 published reports have described associations between single nucleotide polymorphisms (SNPs) and type 2 diabetes. However, multiple studies of the same variant have often been discordant. From a literature search, we identified previously reported type 2 diabetes-associated SNPs. We initially genotyped 134 SNPs on 786 index case subjects from type 2 diabetes families and 617 control subjects with normal glucose tolerance from Finland and excluded from analysis 20 SNPs in strong linkage disequilibrium (r(2) > 0.8) with another typed SNP. Of the 114 SNPs examined, we followed up the 20 most significant SNPs (P < 0.10) on an additional 384 case subjects and 366 control subjects from a population-based study in Finland. In the combined data, we replicated association (P < 0.05) for 12 SNPs: PPARG Pro12Ala and His447, KCNJ11 Glu23Lys and rs5210, TNF -857, SLC2A2 Ile110Thr, HNF1A/TCF1 rs2701175 and GE117881_360, PCK1 -232, NEUROD1 Thr45Ala, IL6 -598, and ENPP1 Lys121Gln. The replication of 12 SNPs of 114 tested was significantly greater than expected by chance under the null hypothesis of no association (P = 0.012). We observed that SNPs from genes that had three or more previous reports of association were significantly more likely to be replicated in our sample (P = 0.03), although we also replicated 4 of 58 SNPs from genes that had only one previous report of association.

"Type 1 on type 2" diabetes mellitus: autoimmune type 1 diabetes superimposed on established type 2 diabetes

OBJECTIVE

To investigate clinical features and pathophysiology of a rare form of new-onset type 1 diabetes mellitus that was superimposed on established type 2 diabetes.

PATIENTS AND METHODS

We retrospectively analyzed 126 consecutive type 2 diabetic patients, who were admitted to the hospital 2 or more times from July 2000 to December 2005 and had been repeatedly examined for islet-associated autoantibodies and insulin secretory capacity over a period of years.

RESULTS

We experienced 2 patients in whom autoantibodies including ICA, GADAb, and IA-2Ab were initially all negative, but in whom at least 1 of these antibodies later became positive, whose endogenous insulin secretion decreased, and who eventually reached an insulin-dependent stage. At the time of seroconversion of antibodies, the patients had 15 to 23 years' history of diabetes, and had microvascular complications specific to diabetes mellitus, and before seroconversion insulin secretory capacities were preserved. The patients had HLA types associated with susceptibility to Japanese type 1 diabetes mellitus.

CONCLUSIONS

Our findings suggest that autoimmune type 1 diabetes mellitus may be superimposed on well-established type 2 diabetes.

Interaction of KIR Genes and G1M Immunoglobulin Allotypes Confer Susceptibility to Type 2 Diabetes in Puerto Rican Americans

The susceptibility to type 2 diabetes (T2D) involves genetic factors. We studied the distribution of KIR and MHC class I ligands phenotype and genotype frequencies, as well as immunoglobulin KM and GM allotype frequencies in a group of patients (N = 95) with T2D and ethnically matched healthy controls (N = 74) with Puerto Rican ethnic background. We found a slight increase of the 2DL3/2DL3 homozygous genotype in T2D. Moreover, the association between 2DL3/2DL3 genotype was significant in the presence of 2DS4 (pC = 0.01). Also, we observed an epistatic effect of the interaction of 2DL3/2DL3, 2DS4 with allele z of G1M in T2D (pC = 0.004, OR = 3.60, 95% CI, 1.62-8.10). This genetic interaction between KIR and G1M allotypes, associated with T2D, was also significant by multiple logistic regression analysis (p < 0.0001, OR = 4.90, 95% CI, 2.12-11.3). We did not detect population stratification using unlinked short tandem repeat (STR) markers, demonstrating that the patients and controls were ethnically matched. Hence, we have demonstrated in this study an epistatic interaction between KIR genes and the G1M allotype that influences the susceptibility to T2D in Puerto Rican Americans. Our findings are important for understanding the autoimmune or innate immune inflammatory-mediated mechanisms involved in the pathogenesis of T2D.

IRS1, KCNJ11, PPARgamma2 and HNF-1alpha: do amino acid polymorphisms in these candidate genes support a shared aetiology between type 1 and type 2 diabetes?

AIMS

Type 1 diabetes mellitus (T1DM) is a chronic disorder primarily triggered by environmental and immunological factors in genetically susceptible individuals. Despite the fact that there are indications of common aetiological features of T1DM and type 2 diabetes (T2DM), variation in genes involved in insulin secretion and insulin signalling has to a large extent been ignored as potential modifiers in the pathogenesis of T1DM. Recent studies suggest, however, that proven T2DM susceptibility gene variants may be involved in the pathogenesis of T1DM. The objective of this study was to estimate the impact of four selected amino acid polymorphisms -IRS-1 Gly972Arg, Kir6.2 Glu23Lys, HNF-1alpha Ala98Val and PPARgamma2 Pro12Ala in a Danish population of T1DM families.

METHODS

All variants were genotyped in 490 simplex- and multiplex-T1DM families applying polymerase chain reaction-restriction fragment length polymorphism, and results were evaluated by means of a transmission disequilibrium test (TDT) analysis.

RESULTS

TDT analysis revealed that the Arg972 IRS-1, the Lys23 Kir6.2 and the Val98 HNF-1alpha variants were transmitted from heterozygous parents to affected probands at frequencies of 49.1%, 47.0% and 54.1%, respectively (p > 0.05 for all). This was similar to the rate of transmission to unaffected siblings. The transmission rate of the Ala12 PPARgamma2 variant to affected probands was 46.5% (p > 0.05) which differed significantly from the transmission to unaffected offspring (p = 0.024). A combined analysis of the present and published pertinent data of 1691 transmissions showed a significantly decreased transmission of the PPARgamma2 Ala12 allele to affected probands (p = 0.0045).

CONCLUSIONS

The Pro12Ala variant of PPARgamma2 is associated with T1DM, the minor Ala allele conferring a reduced risk. This same finding has been reported in patients with T2DM.

Type 1 and type 2 diabetes: what do they have in common?

Type 1 and type 2 diabetes frequently co-occur in the same families, suggesting common genetic susceptibility. Such mixed family history is associated with an intermediate phenotype of diabetes: insulin resistance and cardiovascular complications in type 1 diabetic patients and lower BMI and less cardiovascular complications as well as lower C-peptide concentrations in type 2 diabetic patients. GAD antibody positivity is more common in type 2 diabetic patients from mixed families than from common type 2 diabetes families. The mixed family history is associated with more type 1-like genetic (HLA and insulin gene) and phenotypic characteristics in type 2 diabetic patients, especially in the GAD antibody-positive subgroup. Leaving out the extreme ends of diabetes phenotypes, young children progressing rapidly to total insulin deficiency and strongly insulin-resistant subjects mostly with non-Europid ethnic origin, a large proportion of diabetic patients may have both type 1 and type 2 processes contributing to their diabetic phenotype.

An immune origin of type 2 diabetes?

Subclinical, low-grade systemic inflammation has been observed in patients with type 2 diabetes and in those at increased risk of the disease. This may be more than an epiphenomenon. Alleles of genes encoding immune/inflammatory mediators are associated with the disease, and the two major environmental factors the contribute to the risk of type 2 diabetes-diet and physical activity-have a direct impact on levels of systemic immune mediators. In animal models, targeting of immune genes enhanced or suppressed the development of obesity or diabetes. Obesity is associated with the infiltration and proinflammatory activity of macrophages in adipose tissue, and immune mediators may be important regulators of insulin resistance, mitochondrial function, ectopic lipid storage and beta cell dysfunction or death. Intervention studies targeting these pathways would help to determine the contribution of an activated innate immune system to the development of type 2 diabetes.

Increasing body weight predicts the earlier onset of insulin-dependant diabetes in childhood: testing the 'accelerator hypothesis' (2)

AIMS AND METHODS

It has recently been hypothesized that weight gain in childhood accelerates the onset of Type 1 diabetes, as well as increasing its risk, and that Type 1 diabetes and Type 2 diabetes may be one and the same disorder of insulin resistance. An explanation is needed for the rising incidence of childhood diabetes and, to test the Accelerator Hypothesis, we examined the anthropometric measurements recorded from birth in 168 young people presenting with Type 1 diabetes between 1980 and 2002. Pre-onset as well as peri- and post-onset measurements of height and weight were available, and waist circumference was recorded at various intervals after onset.

RESULTS

The mean birth weight of the children and their height, weight and body mass index (BMI) at diagnosis lay close to the population mean. However, pre-onset and post-onset BMI were both well above the population mean, were closely correlated with each other (r = 0.79, P < 0.001) and (inversely) with age at onset (r = -0.30, P < 0.001). A significant correlation was also found between BMI standard deviation scores (sds) and year of diagnosis (r = 0.27, P < 0.001) and, importantly, waist circumference sds in the children with Type 1 diabetes was found to be substantially greater than average for the population [boys: +0.96 (sd 1.04), girls: +1.30 (sd 0.89)].

CONCLUSIONS

The data suggest that children with Type 1 diabetes have become progressively heavier at diagnosis over the past 20 years, and that the heavier child develops it earlier. Waist circumference, a proxy for visceral fat mass and insulin resistance, is substantially greater in children with Type 1 diabetes. Weight centile crossing appears to be an important environmental accelerator which may contribute to or account for the striking increase in both Type 1 diabetes and Type 2 diabetes in childhood. A reduction of body weight and improved lifestyle might reverse this trend in both types of diabetes.

Analysis of the type 2 diabetes-associated single nucleotide polymorphisms in the genes IRS1, KCNJ11, and PPARG2 in type 1 diabetes

It has been proposed that type 1 and 2 diabetes might share common pathophysiological pathways and, to some extent, genetic background. However, to date there has been no convincing data to establish a molecular genetic link between them. We have genotyped three single nucleotide polymorphisms associated with type 2 diabetes in a large type 1 diabetic family collection of European descent: Gly972Arg in the insulin receptor substrate 1 (IRS1) gene, Glu23Lys in the potassium inwardly-rectifying channel gene (KCNJ11), and Pro12Ala in the peroxisome proliferative-activated receptor gamma2 gene (PPARG2). We were unable to confirm a recently published association of the IRS1 Gly972Arg variant with type 1 diabetes. Moreover, KCNJ11 Glu23Lys showed no association with type 1 diabetes (P > 0.05). However, the PPARG2 Pro12Ala variant showed evidence of association (RR 1.15, 95% CI 1.04-1.28, P = 0.008). Additional studies need to be conducted to confirm this result.

HLA haplotype is associated with diabetes among atomic bomb survivors

We examined radiation effects on the relationship between diabetes development and genetic background in atomic-bomb (A-bomb) survivors. Our main aim in this study was to shed light on the role of genetic background in diabetes onset among A-bomb survivors by studying possible relationships between human leukocyte antigen (HLA) genotypes and the diabetes in patients and controls. We examined the effects of different HLA haplotypes on type 2 diabetes development by determining the DQA1 and DRB1 alleles of Hiroshima A-bomb survivors (111 diabetic patients and 774 controls) using the polymerase chain reaction-sequence specific oligonucleotide probes (PCR-SSOP) method. We noted an increased risk of diabetes in the higher dose group among these patients (trend p = 0.001). The risk of the most heavily exposed group was significantly higher than that of the unexposed group or the low-dose group especially in survivors with the DQA1*03-DRB1*09 or DQA1*0401-DRB1*08 haplotypes (trend p = 0.002 or p = 0.05, respectively). By contrast, in people with other haplotypes, the risk did not increase significantly with increasing dose. These results suggest that individuals with specific HLA haplotypes may have an increased risk of diabetes with increased-dose categories.

Protective effect of DRB1 locus against type 2 diabetes mellitus in Mexican Mestizos

The aim of the study was to investigate the participation of human leukocyte antigen (HLA) class II alleles in the expression of type 2 diabetic and in nondiabetic subjects with and without family history of diabetes. The purpose was to evaluate any HLA association and to look for different patterns of insulin resistance and insulin secretion, comparing subjects with a low probability of developing diabetes, as a result of their family history. We recruited 87 healthy subjects without family history of diabetes, 48 healthy subjects with family history, and 47 type 2 diabetic patients. All of them were Mexican Mestizos of central Mexico. Using a standard 75-g oral glucose tolerance test, insulin resistance was determined and insulin secretion was assessed with the HOMA model. DRB1, DQA1 and DQB1 alleles were typed using polymerase chain reaction-sequence-specific oligonucleotide probe (PCR-SSOP) and sequence specific primers (PCR-SSP). Nondiabetic subjects had similar HOMA-IR and DeltaI 30/DeltaG 30 index (HOMA). A significant decreased frequency of DRB1*0403 (p = 0.01; odds ratio [OR] = 0.20) was demonstrated in type 2 diabetic patients, and DRB1*0701 (p = 0.02; OR = 0.17) in nondiabetics with family history of diabetes. These alleles associated with protection against type 2 diabetes, share glutamic acid at position-74 and were previously demonstrated to contribute to protection against type I diabetes.

Association of the tumour necrosis factor alpha -308G/A polymorphism with the risk of diabetes in an elderly population-based cohort

Ample evidence supports a role for tumour necrosis factor alpha (TNFalpha) in the development of type 2 diabetes and cardiovascular disease. TNFalpha expression was found to be influenced by a -308G/A polymorphism in the promoter of the gene encoding TNFalpha (TNF). We investigated the contribution of this polymorphism to diabetes and cardiovascular mortality in a population-based cohort of 664 subjects aged 85 years and over (Leiden 85-plus Study). The -308G/A TNF promoter polymorphism was associated with the prevalence of diabetes in old age (P = 0.006). The risk of diabetes among subjects homozygous for the A-allele was estimated to be 4.6-fold (95% CI, 1.6-13.3) higher than among subjects homozygous for the common G-allele. The promoter polymorphism did not, however, predict mortality from all causes, cardiovascular diseases, cancer or infectious diseases during a 10-year follow-up period. In addition to the promoter polymorphism, TNFa and TNFc microsatellite genotypes were determined but these polymorphisms were not associated with morbidity or mortality. In conclusion, the -308G/A polymorphism in the TNF promoter is strongly associated with the risk of diabetes but not cardiovascular mortality in old age.

Prevalence and features of pancreatic islet cell autoimmunity in women with gestational diabetes from different ethnic groups

OBJECTIVE

To assess the prevalence and characteristics of islet cell autoimmunity amongst women with gestational diabetes selected from South Asian and Afro-Caribbean as well as European populations.

DESIGN

Cross-sectional retrospective survey of subject cohort.

POPULATION

Three hundred and twenty-one women with a recent history of gestational diabetes (173 European, 86 South Asian and 62 Afro-Caribbean), a median (range) of 22 (1-150) months postpartum.

RESULTS

Antibodies to Glutamic acid decarboxylase were found in 13 (4%) of these women. There was no difference in the prevalence of anti-glutamic acid decarboxylase positivity between the three ethnic groups (European 4.6%, South Asian 3.5%, Afro-Caribbean 3.2%). Anti-glutamic acid decarboxylase positive women were leaner than anti-glutamic acid decarboxylase negative women (body mass index, median (upper-lower quartile) 23.9 (22.5-26.7) vs 26.6 (23.4-30.5)kg/m2, P = 0.03, P = 0.049 allowing for ethnicity). There was no difference between glutamic acid decarboxylase-positive and glutamic acid decarboxylase-negative women for age, family history of diabetes, waist/hip ratio, prevalence of insulin treatment during pregnancy, postpartum glucose status, lipid profile and indices of insulin action and beta-cell function.

CONCLUSIONS

Markers of islet cell autoimmunity are found as frequently in gestational diabetes women of South Asian and Afro-Caribbean origin, as they are in European subjects. Identification of future risk of type 1 diabetes is relevant to the planning of clinical management and intervention strategies in women with gestational diabetes of all major ethnic groups.

Type 1 diabetes in the offspring does not increase the risk of parental type 2 diabetes in South Indians

OBJECTIVES

(a) To study whether there was an increased prevalence of glucose intolerance in the parents of probands with Type 1 diabetes and (b) to look for any possible link between the glucose intolerance in the parents with HLA-DQB1 alleles transmitted in excess to the Type 1 diabetes offspring. Study Design and Methods From 215 families of South Indian Type 1 diabetes probands, 336 parents (170 fathers, age 30-70 years; 166 mothers, age 23-72 years) were studied by oral glucose tolerance test (GTT). Glucose intolerance in the parents was compared with the population data available. HLA-DQB1 alleles in 170 of the families were studied by the Olerup method (based on sequence specific primers) and the transmission disequilibrium test (TDT) was used to determine the Type 1 diabetes-associated DQB1 alleles.

RESULTS

Among the parents 11.2% had Type 2 diabetes which was similar to the population data of 11.6%. However there was a male predominence among the diabetic parents (chi(2)=7.0, p=0.008), while in the population there was a female predominence. Prevalence of IGT was significantly more among the parents (13.6%) compared with the population data (9.1%) (chi(2)=6.43, p=0.011). Both HLA-DQB1*0201 (p<0.0001) and DQB1*0302 (p=0.0001) were positively associated with Type 1 diabetes in the probands although 21% of the probands possessed neither DQB1*0201 or DQB1*0302. The distribution of glucose tolerance categories in the parents of the probands differed according to the presence of DQB1*0302 (p= 0.035) whilst no such differences existed for DQB1*0201.

CONCLUSIONS

In summary, the presence of Type 1 diabetes in the South Indian offspring does not predict a higher occurrence of Type 2 diabetes in the parents. However, there is an increased occurrence of impaired glucose tolerance (IGT) among the parents. Family based studies demonstrate increased transmission of HLA-DQB1*0201 and HLA-DQB1*0302 with Type 1 diabetes similar to North American and European Caucasian subjects. Furthermore, HLA-DQB1*0302 may be a minor determinant of glucose tolerance in parents of offspring with Type 1 diabetes.

Pharmacological management of diabetes: recent progress and future perspective in daily drug treatment

Glycaemic control in Type 1 diabetes has been proven efficient in preventing microvascular and neurological complications. The assumption that good control of hyperglycaemia may also have significant impact on alleviation of complications in Type 2 diabetes has gained growing support in recent years. Measures such as body weight reduction and exercise improve the metabolic defects, but pharmacological therapy is most frequently used. The sulphonylureas stimulate insulin secretion. Metformin and troglitazone increase glucose disposal and decrease hepatic glucose output without causing hypoglycaemia. Acarbose helps to spread the dietary carbohydrate challenge to endogenous insulin over time. These pharmacological treatments can improve blood glucose regulation in Type 2 diabetes patients. However, the key to strict glycaemic control with use of exogenous insulin lies in the creation of delivery methods that emulate physiologic insulin secretion. Insulin lispro, a recombinant insulin analogue, is identical to human insulin except for the transposition of proline and lysine at positions 28 and 29 in the C-terminus of the B chain. Evidence suggests that patients perceive their quality of life to be improved with insulin lispro when compared with regular human insulin, and that satisfaction with treatment is greater with the insulin analogue. Numerous new pharmacological approaches are under active investigation, with the aim of promoting insulin secretion, improving the action of insulin, or slowing carbohydrate absorption. With respect to continuous subcutaneous insulin infusion therapy and implantable pumps, despite that this approach is not widely utilised, it appears to bring us as close to achieving glycaemic control as is feasible with current treatment approaches. However, general application of such technology requires significant improvements in several areas, such as improvement of patency of catheter, pump failures due to early battery depletion incidents, and pump miniaturisation. Future perspective resides on insulin analogues with longer half-lives that would provide better basal insulin coverage in association with fast-acting analogues.

An autosomal genomic scan for loci linked to type II diabetes mellitus and body-mass index in Pima Indians

Genetic factors influence the development of type II diabetes mellitus, but genetic loci for the most common forms of diabetes have not been identified. A genomic scan was conducted to identify loci linked to diabetes and body-mass index (BMI) in Pima Indians, a Native American population with a high prevalence of type II diabetes. Among 264 nuclear families containing 966 siblings, 516 autosomal markers with a median distance between adjacent markers of 6.4 cM were genotyped. Variance-components methods were used to test for linkage with an age-adjusted diabetes score and with BMI. In multipoint analyses, the strongest evidence for linkage with age-adjusted diabetes (LOD = 1.7) was on chromosome 11q, in the region that was also linked most strongly with BMI (LOD = 3.6). Bivariate linkage analyses strongly rejected both the null hypothesis of no linkage with either trait and the null hypothesis of no contribution of the locus to the covariation among the two traits. Sib-pair analyses suggest additional potential diabetes-susceptibility loci on chromosomes 1q and 7q.

Insulin resistance versus insulin deficiency in non-insulin-dependent diabetes mellitus: problems and prospects

A definitive assessment of the relative roles of insulin resistance and insulin deficiency in the etiology of NIDDM is hampered by several problems. 1) Due to better methodology, data on insulin resistance are generally more accurate and consistent than data on insulin deficiency. 2) In source data, case-control studies are prone to selection bias, while epidemiological associations, whether cross-sectional or longitudinal, are liable to misinterpretation. 3) Insulin secretion and action are physiologically interconnected at multiple levels, so that an initial defect in either is likely to lead with time to a deficit in the companion function. The fact that both insulin resistance and impaired insulin release have been found to precede and predict NIDDM in prospective studies may be in part a reflection of just such relatedness. 4) Direct genetic analysis is effective in rarer forms of glucose intolerance (MODY, mitochondrial mutations, etc.) but encounters serious difficulties with typical late-onset NIDDM. Despite these uncertainties, the weight of current evidence supports the view that insulin resistance is very important in the etiology of typical NIDDM for the following reasons: 1) it is found in the majority of patients with the manifest disease; 2) it is only partially reversible by any form of treatment (117); 3) it can be traced back through earlier stages of IGT and high-risk conditions; and 4) it predicts subsequent development of the disease with remarkable consistency in both prediabetic and normoglycemic states. Of conceptual importance is also the fact that the key cellular mechanisms of skeletal muscle insulin resistance (defective stimulation of glucose transport, phosphorylation, and storage into glycogen) have been confirmed in NIDDM subjects by a variety of in vivo techniques [ranging from catheter balance (118) to multiple tracer kinetics (119) to 13C nuclear magnetic resonance spectroscopy (120)], and have been detected also in normoglycemic NIDDM offspring (121). If insulin resistance is a characteristic finding in many cases of NIDDM, insulin-sensitive NIDDM does exist. On the other hand, given the tight homeostatic control of plasma glucose levels in humans, beta-cell dysfunction, relative or absolute, is a sine qua non for the development of diabetes. If insulin deficiency must be present whereas insulin resistance may be present, is this proof that the former is etiologically primary to the latter? If so, do we have convincing evidence that the primacy of insulin deficiency is genetic in nature? The answer to both questions is negative on several accounts. The defect in insulin secretion in overt NIDDM is functionally severe but anatomically modest: beta-cell mass is reduced by 20-40% in patients with long-standing NIDDM (122). Moreover, the insulin secretory deficit is progressively worse with more severe hyperglycemia (123) and recovers considerably upon improving glycemic control (124). These observations indicate that part of the insulin deficiency is acquired (through glucose toxicity, lipotoxicity, or both). In addition, although insulin deficiency is necessary for diabetes, it may not always be sufficient to cause NIDDM. In fact, subtle defects in the beta-cell response to glucose may be widespread in the population (108, 125) and only cause frank hyperglycemia when obesity/insulin resistance stress the secretory machinery. Conceivably, there could be beta-cell dysfunction without NIDDM just as there is insulin resistance without diabetes. Incidentally, any defect in insulin secretion, whether in normoglycemic or hyperglycemic persons, could be due to other factors than primary beta-cell dysfunction: amyloid deposits in the pancreas (126), changes in insulin secretagogues (amylin, GLP-1, GIP, galanin) (127-130), early intrauterine malnutrition (131). Finally, the predictive power of early changes in insulin secretion for the development of typical NIDDM is generally lower than that of insulin

Non-insulin-dependent diabetes mellitus--a collision between thrifty genes and an affluent society

Non-insulin-dependent diabetes mellitus (NIDDM) is one of the most common non-communicable diseases in the world. It has become obvious that NIDDM is the result of a collision between thrifty genes and an affluent society. Genes predisposing to NIDDM might have been survival genes for our ancestors, helping them to store energy during long periods of starvation. When these genes are exposed to a sedentary lifestyle and high caloric intake typical to the Western world, they predispose to obesity and insulin resistance. NIDDM results when beta cells cannot compensate for insulin resistance by increasing insulin secretion. Therefore, at least two inherited defects can be expected in NIDDM, one causing obesity and insulin resistance and the other inability to increase insulin secretion. In reality there may be more inherited defects. It has become quite clear that diabetes cannot simply be divided into NIDDM and insulin-dependent diabetes mellitus (IDDM). The disease is more heterogeneous; unmasking this heterogeneity and identifying new subgroups of diabetes presents a challenge to modern molecular biology.

Low prevalence of immunogenetic markers of IDDM in adult Koreans with diabetes detected on OGTT

In the Asian populations, it is not uncommon for adult patients with NIDDM to eventually lose beta-cell function and develop IDDM. Accepting that IDDM is an autoimmune disease, which occurs on a genetic background, it could by hypothesized that by measuring autoantibody prevalence and HLA DQ gene polymorphism, known important prediagnostic markers of IDDM, the prevalence of adult-onset IDDM in patients with previously undiagnosed NIDDM patients could be estimated. To do this, anti-GAD prevalence and HLA DQ A1 and DQ B1 polymorphisms after PCR amplification of genomic DNA were analyzed in 121 newly diagnosed diabetic patients of Yonchon cohort and compared to the results with those of 100 matched health control subjects. We also compared the results with those of other populations to assess the difference of genotype distribution. The overall prevalence of anti-GAD antibodies was 1.7% (2 of 121) in patients with previously undiagnosed NIDDM, whereas 1 of 100 controls had positive antibodies. Among those who were positive, their titer of antibodies to GAD were not high. No statistically significant differences in the distribution of either mean levels of anti-GAD or DQA1 and DQB1 alleles were found comparing NIDDM patients to controls. Interestingly, the frequency of DQB1*non-Asp-57 and DQA1*Arg-52 alleles in the Korean adult control population was similar to that of US Caucasians (DQB1*non-Asp-57: 0.431 vs. 0.475; DQA1*Arg-52: 0.492 vs. 0.463). The low prevalence of anti-GAD antibodies and HLA-DQA1 and DQB1 susceptibility alleles among recent-onset NIDDM patients, not different compared to controls suggests that diabetes in Korean adults is unlikely to have an autoimmune component to its pathogenesis.

Genetics of non-insulin-dependent (type-II) diabetes mellitus

Both genetic and environmental factors contribute to the etiology of non-insulin-dependent diabetes. The genetic component is heterogeneous and in some patients is probably complex, involving multiple genes. Specific genetic defects have been identified for rate monogenic forms of NIDDM: maturity-onset diabetes of the young, or MODY (which is due to glucokinase mutations in about 40% of families), syndromes of extreme insulin resistance (which often involve the insulin receptor), and diabetes-deafness syndromes (with defects in mitochondrial genes). In contrast, the genes involved in common forms of NIDDM are still uncertain. Mutations have been extensively searched in genes regulating insulin signaling and secretion. Some evidence of involvement has been produced for insulin-receptor substrate-1, glycogen synthase, the glucagon receptor, a ras-related protein (Rad), histocompatibility antigens, PC-1, and fatty acid binding protein, but the contributions of these genes to NIDDM is probably small. Other candidate genes (e.g. insulin, insulin receptor, glucose transporters) have been excluded as major diabetogenes. New insights are expected in the near future from the systematic scanning of the genome for linkage with NIDDM.

In Finland insulin gene region encoded susceptibility to IDDM exerts maximum effect when there is low HLA-DR associated risk. DiMe (Childhood Diabetes in Finland) Study Group

An association between insulin-dependent diabetes mellitus (IDDM) and polymorphisms of the insulin gene on chromosome 11p15 (INS) is a consistent finding in Europid populations. While one study suggested that the INS association is restricted to HLA-DR4-positive individuals, studies in other Europid populations have shown the disease-associated INS genotype to confer susceptibility independently of HLA-DR. We have investigated the role of INS in susceptibility to IDDM in Finland, which has the highest incidence of diabetes mellitus in the world, at two polymorphic restriction sites, 5' and 3' to the insulin gene. From the DiMe (Childhood Diabetes in Finland) Study we studied 154 diabetic children without regard to HLA-DR type; 108 DR4 positive/non-DR3 diabetic children; 39 DR3 positive/non-DR4 diabetic children; 30 DR4/DR3 positive diabetic children; 31 non-DR4/non-DR3 diabetic children; 96 matched DiMe control subjects and 86 other healthy, non-diabetic Finnish control subjects. We found an overall association between IDDM and INS in the high-risk Finnish population only with the 5' polymorphism and identified an INS haplotype negatively associated with IDDM in Finland. However, among diabetic subjects with a reduced HLA-associated susceptibility (non-DR4/non-DR3) both 3' and 5' INS loci showed an association with IDDM (p values 0.02 and 0.0002, respectively). Thus, in the Finnish population insulin gene-encoded susceptibility to IDDM exerts a maximum effect in those with reduced HLA-associated risk.

Variation of diabetes mellitus prevalence in general practice and its relation to deprivation

This is an observational study to compare age standardized diabetes prevalences and relate these to socio-economic measures of deprivation. It includes data from eight general (family) practices in the Bristol, UK, area with no ethnic minorities affecting diabetes prevalence. A total population of 71 599 was covered, including 181 Type 1 and 901 Type 2 diabetic patients, 91 of whom were controlled with insulin, 499 with oral hypoglycaemics, and 311 with diet alone. Actual Type 1 and Type 2 diabetes prevalences were standardized to what they would be if each practice had the UK national age profile. Total standardized diabetes prevalence varied from 1.31% to 2.51% (p < 0.001) and Type 2 diabetes prevalence from 0.97% to 2.29% (p < 0.001). There was no significant variation in the prevalence of Type 1 diabetes. The Spearman rank correlation coefficient indicated a significant association between standardized diabetes prevalence and two measures, the Jarman and Townsend indices, of deprivation in the electoral ward where each practice was situated. Total standardized diabetes prevalence was significantly correlated with each of the Jarman and Townsend indices (r = 0.76, p < 0.05). Standardized Type 2 diabetes prevalence was similarly significantly correlated to each deprivation index (rs = 0.74, p < 0.05). Type 2 diabetes prevalence is affected by socio-economic factors with implications for health targets and capitation based budgets.

Pathogenesis of feline diabetes mellitus

Cats are one of the few species that develop a form of diabetes mellitus that is clinically and histologically analogous to human type 2 diabetes mellitus. Figure 9 summarizes the etiologic factors thought to be involved in the development of feline and human type 2 diabetes. The main metabolic characteristics of type 2 diabetes mellitus are impaired insulin secretion and resistance to the action of insulin in its target tissues. Impaired beta cell function occurs before histologic changes become evident. The characteristic histologic finding in cats with type 2 diabetes is deposition of amyloid in pancreatic islets. Amyloid deposition occurs before the onset of clinical signs, but does not seem to be the primary defect. Pancreatic amyloid is derived form the recently discovered pancreatic hormone amylin. Amylin is synthesized in pancreatic beta cells, and is co-stored and co-secreted with insulin. Amylin has been postulated to be involved in the pathogenesis of feline diabetes mellitus both through its metabolic effects, which include inhibition of insulin secretion and induction of insulin resistance, and via progressive amyloid deposition and beta cell degeneration. Increased amylin concentration has been documented intracellularly in cats with impaired glucose tolerance and in the plasma of diabetic cats, and supports the hypothesis that amylin is involved in the pathogenesis of type 2 diabetes. Obesity is a common finding in diabetic felines and is a contributing factor to the insulin resistance present in type 2 diabetes. Clinical signs of diabetes develop once total insulin secretion decreases to 20% to 25% of normal levels. Many diabetic cats have been treated successfully with oral hypoglycemics, but 50% to 70% of diabetic cats are insulin dependent. Based on histologic evidence, this is the result of extensive amyloid deposition and subsequent beta cell degeneration, rather than autoimmune destruction of pancreatic beta cells associated with type 1 diabetes. Alternative ways of treating type 2 diabetes currently are being investigated. Amylin antagonists recently have been proposed as a novel treatment to reverse the deleterious effects of excessive amylin concentrations. The gastrointestinal hormone glucagon-like peptide-1 may also prove useful in treating diabetic cats, because of its stimulatory effect on insulin secretion and synthesis, and the absence of significant hypoglycemic effect.

Insulin receptor substrate-1 gene mutations in NIDDM; implications for the study of polygenic disease

Variations in the coding regions of the insulin receptor substrate-1 (IRS-1) gene have recently been suggested to contribute to the susceptibility of non-insulin-dependent diabetes mellitus (NIDDM). The purpose of this study was to examine the role of the IRS-1 missense mutations at codons 972 (glycine to arginine) and 513 (alanine to proline) in two diverse populations from South India and Finland at high risk for NIDDM. DNA was amplified and digested with restriction enzymes BstN1 to detect the codon 972 mutation and Dra III to detect the codon 513 mutation. The codon 513 mutation was not found in the study subjects. The codon 972 mutation was present in 10.3% of 126 middle-aged NIDDM subjects and 5.3% of 95 matched control subjects in the South Indians (p = 0.17). In elderly Finnish subjects the frequency of the mutation was 7.5% in 40 NIDDM subjects and 7% in 42 matched control subjects. The frequency of codon 972 mutation in the South Indian NIDDM subjects was very similar to the two previously published studies in Danish and French subjects although each study individually fails to reach conventional levels of significance. The data from all four ethnic groups were analysed together after ascertaining that significant heterogeneity did not exist between the studies. Overall, the frequency of the codon 972 mutation is found in 10.7% NIDDM subjects and 5.8% control subjects (p = 0.02). These studies suggest that the codon 972 mutation of the IRS-1 gene might act as a susceptibility gene predisposing to NIDDM in certain ethnic groups.

Frequency of diabetes in family members of probands with non-insulin-dependent diabetes mellitus

OBJECTIVES

To describe the prevalence of known diabetes in a multi-ethnic community in South Auckland, New Zealand, in relation to family history of diabetes and past history of diabetes in pregnancy.

DESIGN

A cross-sectional, household survey comparing ascertainment with local general practice diabetes registers where they existed.

SETTING

An inner-city community with a high proportion of Maori, Pacific Islands people and Europeans.

SUBJECTS

A total of 55,518 residents (91% response). Comparison with diabetes registers showed 91% ascertainment of known diabetic residents. More detailed interviews with 176/214 (82%) Europeans, 286/336 (85%) Maori and 495/585 (85%) Pacific Islands people with known diabetes. Fifty subjects had insulin-dependent diabetes mellitus on clinical criteria and were excluded from analyses.

MAIN OUTCOME MEASURES

Prevalence of diabetes.

RESULTS

Those with non-insulin-dependent diabetes mellitus were more likely to have a diabetic mother than father (Europeans, 21.7% vs. 9.9%; Maori, 17.6 vs. 11.4%; Pacific Islands, 15.7 vs. 5.3%). Diabetic women had a similar likelihood of having a diabetic father as diabetic men but were 1.84 times as likely to have a diabetic mother (95% CI, 1.27-2.69). Diabetic women with past diabetes in pregnancy had 2.05 (95% CI, 1.01-4.15) times the chance of a diabetic offspring as women who had not had past diabetes in pregnancy, who in turn had 2.69 (95% CI, 1.17-6.18) times the likelihood of having a diabetic offspring as diabetic men.

CONCLUSIONS

The mother is a more important conduit for inheritance of diabetes than the father in these three ethnic groups. A history of diabetes in pregnancy confers an extra risk to the offspring above this usual maternal excess.

A gene in the HLA class I region contributes to susceptibility to IDDM in the Finnish population. Childhood Diabetes in Finland (DiMe) Study Group

In Finland the haplotype A2, Cw1, B56, DR4, DQ8 is the third most common haplotype in insulin-dependent diabetic (IDDM) patients and has the highest haplotype-specific absolute risk for IDDM. Cw1, B56, DR4, DQ8 haplotypes containing HLA-A alleles other than A2 are infrequent in the population and are not associated with IDDM. Comparison of the A2 and non-A2 haplotypes at the DNA level showed that they were identical at HLA-B, -DR, and -DQ loci. Evidence that class I alleles confer susceptibility to IDDM was obtained from the two HLA-C, -B, -DR and -DQ haplotypes most frequently found in IDDM patients in Finland. A24, A3 and A2 on the Cw3, B62, DR4, DQ8 haplotype, and A28, A2 and A1 on the Cw7, B8, DR3, DQ2 were all found to be associated with IDDM. In Finland these seven haplotypes, including A2, Cw1, B56, DR4, DQ8, account for 33% of diabetic haplotypes and 10.3% of non-diabetic haplotypes (p < 0.00001). The contribution of the class I region to IDDM susceptibility was also apparent in those IDDM patients lacking the disease-predisposing class II alleles. Significantly more non-DR3/non-DR4 IDDM patients (47 of 55) possessed two of the IDDM-associated HLA-A alleles compared to non-DR3/non-DR4 control subjects (40 of 58; p = 0.038). Moreover, IDDM patients confirmed by oligotyping as unable to form a 'diabetes-susceptibility' DQ heterodimer, tended to possess two diabetes-associated HLA-A alleles (12 of 13) compared to control subjects (12 of 20; p = 0.056).

Antibodies to glutamic acid decarboxylase as predictors of insulin-dependent diabetes mellitus before clinical onset of disease

We have done a study designed to ascertain the effectiveness of measuring antibodies to glutamic acid decarboxylase (anti-GAD) in predicting insulin-dependent diabetes mellitus (IDDM). Anti-GAD was measured in prediabetic sera from 151 women aged 20-39 years with newly diagnosed diabetes mellitus who had been identified through a nationwide diabetes register. Multiple serum samples had been collected from these women up to 10 years before the clinical onset of diabetes during their earlier pregnancies. Anti-GAD was measured with a radioimmunoprecipitation assay. Anti-GAD was detected in 82% of 28 women with IDDM, in 36% of 11 women with non-insulin-dependent diabetes mellitus, and in 5% of 112 women with gestational diabetes mellitus. In a random sample of 100 non-diabetic young Finnish women, none had anti-GAD. The sensitivity of the anti-GAD assay for predicting IDDM was 82.1% and the specificity was 100%. The longest time of anti-GAD positivity before clinical onset of IDDM was 10 years. Once positive, anti-GAD levels remained stable and no patients became negative after a positive test during the prediabetic period. Anti-GAD is a valuable early predictive marker and is associated with a very high risk for development of IDDM.

Glucokinase gene polymorphisms: a genetic marker for glucose intolerance in a cohort of elderly Finnish men

Although mutations in the glucokinase gene are implicated in the pathogenesis of glucose intolerance in pedigrees with maturity-onset diabetes of the young, the role of such mutations in typical Type 2 diabetes is poorly characterized. We studied a cohort of elderly men born (between 1900 and 1919) in two Finnish communities and exhibiting a continuous spectrum of glucose tolerance at assessments made in 1984 and 1989. Individuals were typed at two polymorphic microsatellites straddling the glucokinase gene, GCK(3') (n = 169) and GCK(5') (n = 166): these two markers were in linkage equilibrium in this cohort. Significant associations between alleles at the GCK(3') marker and glucose tolerance were evident (p = 0.002), the frequency of the (z + 2) allele rising from zero in control subjects (n = 88 chromosomes) to 6.5% (n = 62) in subjects with impaired tolerance and 12.2% (n = 188) in subjects with diabetes. Mean 2-h glucose levels were 10.5 (9.6-11.4, 95% confidence interval) mmol l-1 in individuals with the (z + 2) allele and 8.1 (7.6-8.7) mmol l-1 in those without (p = 0.01, corrected for multiple comparisons). No association was evident between GCK(5') alleles and glucose tolerance. The GCK(3') microsatellite is a marker for abnormal glucose tolerance in this cohort of elderly Finnish men.