Increased risk of diabetes in first-degree relatives of young-onset type 2 diabetic patients compared with relatives of those diagnosed later

Friedreich's Ataxia related Diabetes: Epidemiology and management practices

AIMS

Friedreich's Ataxia (FRDA) is a progressive neuromuscular disorder typically caused by GAA triplet repeat expansions in both frataxin gene alleles. FRDA can be complicated by diabetes mellitus (DM). The objective of this study was to describe the prevalence of, risk factors for, and management practices of FRDA-related DM.

METHODS

FACOMS, a prospective, multi-site natural history study, includes 1,104 individuals. Extracted data included the presence of DM and other co-morbidities, genetic diagnosis, and markers of disease severity. We performed detailed medical record review and a survey for the subset of individuals with FRDA-related DM followed at one FACOMS site, Children's Hospital of Philadelphia.

RESULTS

FRDA-related DM was reported by 8.7% of individuals. Age, severe disease, and FRDA cardiac complications were positively associated with DM risk. FRDA-related DM was generally well-controlled, as reflected by HbA1c, though diabetic ketoacidosis did occur. Insulin is the mainstay of treatment (64-74% overall); in adults, metformin use was common and newer glucose-lowering agents were used rarely.

CONCLUSIONS

Clinical factors identify individuals at increased risk for FRDA-related DM. Future studies should test strategies for FRDA-related DM screening and management, in particular the potential role for novel glucose-lowering therapies in preventing or delaying FRDA-related cardiac disease.

Type 2 diabetes mellitus risk assessment among doctors in Ondo state

Introduction

Diabetes Mellitus (DM) has become a disease of public health importance in Nigeria. Early identification of DM risk is important in the reduction of this disease burden. This study assessed ten-year risk of developing type 2 DM among some medical doctors in Ondo State.

Methods

This was a cross-sectional study that assessed ten-year risk of developing type 2 DM among some doctors using the Finland Diabetic Risk Score form. Known diabetics were excluded from the study. Body mass index (BMI), waist circumference (WC), blood pressure and total DM risk score were determined for each participant.

Results

One hundred and ninety-two doctors participated in the study with a male: female ratio of 1.3:1. Majority (92.2%) were below 55 years, 22 (11.5%) were obese, 32(16.7%) had central obesity, 46(24%) reported physical inactivity, 49(25.5%) had family history of DM, 141(73.4%) do not take fruits and vegetables regularly. Forty-three (22.4%) were found to have elevated blood pressure while 6(3.1%) had elevated blood glucose. Fifty-seven (29.7%) of the participants had increased ten-year DM risk. Significant predictors of increase DM risk were age ≥ 45 years (AOR:9.08; CI 3.13–26.33; p = <0.001); BMI ≥25kg/m² (AOR:11.41; CI:4.14–31.45; p = <0.001); family history of DM (AOR:9.93; CI:3.25–30.39; p = <0.001); abdominal obesity (AOR:6.66; CI:2.08–21.29; p= < 0.001); and infrequent dietary intake of fruits and vegetable (AOR:3.11;CI:1.03:9.37: p = 0.04)

Conclusion

There was increased 10-year DM risk in about 30% of the participants. Lifestyle modification such as physical activity and regular consumption of fruits and vegetables should be encouraged among doctors.

Genetic association of insulin receptor substrate-1 (IRS-1, rs1801278) gene with insulin resistant of type 2 diabetes mellitus in a Pakistani population

Insulin resistance (IR), a pathological condition of type 2 diabetes mellitus (T2DM) is characterized by an inability of body's tissue to respond the secreted or administered insulin, a necessary step for cellular glucose transportation. The prevalence of insulin resistance progresses with age, especially in overweight people with central obesity. Insulin receptor substrates (IRS) are important molecular proteins in the insulin signalling pathway, where IRS-1 plays a key function in cells insulin sensitivity. The common mutation (rs1801278; r.2963G > A: Gly972Arg) of the IRS-1 gene occurs when residue glycine changes to arginine at codon 972. The objective of this study was to detect the genetic association of rs1801278 polymorphism of the IRS-1 gene with insulin resistance in type 2 diabetes from the Lahore region of Pakistan. A total of 322 subjects (161 cases and 161 healthy individuals) were included. DNA was isolated for detection of the genotype distribution and allele frequencies by PCR-RFLP. The results showed a significant difference in the genotype distribution and allele frequency between the T2DM cases and controls for single nucleotide polymorphism (SNP) rs1801278 (OR 17.61, 95% CI 8.06-38.4, p < 0.001). In conclusion, association between rs1801278 polymorphism of the IRS-1 gene and insulin resistance in T2DM has been established in a Pakistani population.

Assessment of some traditional cardiovascular risk factors in medical doctors in Southern Nigeria

INTRODUCTION

Almost one third of deaths globally are caused by cardiovascular diseases (CVDs). Certain occupations may promote the development and worsening of risk factor for CVDs. We assessed some traditional cardiovascular risk factors and lifestyle choices that may predispose to CVDs in medical doctors in a tertiary health facility in Southern Nigeria.

STUDY DESIGN

Cross-sectional study.

PARTICIPANTS AND METHODS

One hundred sixty-nine apparently healthy medical doctors were recruited. A structured self-administered questionnaire was used to gather data on CVD risk factors. Anthropometric and blood pressure (BP) measurements were taken.

RESULTS

Majority were males (68.0%), aged 20-39 years (43.8%), single (62.7%), and house officers (58.0%) with<1 year (48.5%) work experience. Over half were either overweight or obese. While 77.2% of those not centrally obese were males, only about 22.8% of females did not meet the criteria for central obesity (P-value < 0.05). While respondents had BP in prehypertensive (48.2%), stage 1 (18.5%), or stage 2 hypertension (3.6%) ranges, only 7.7% had a previous diagnosis of hypertension. Only 25.4% took fruits on a daily basis and engaged in aerobic exercises up to 30 minutes daily or at least 3-5 times a week. Other poor lifestyle choices included non-lean meat intake (76.8%), low water intake (88.2%), and junk food and soda drinks intake (daily 28%, weekly 51.2%).

CONCLUSION

Findings of a high prevalence of overweight/obesity, physical inactivity, and junk food intake and low fruits intake among doctors is worrisome. There is a need to educate doctors on adopting healthier lifestyles to reduce risk of CVDs.

Just Living With Obese Family Members Increases Your Risk of Type 2 Diabetes

IN BRIEF In this new era of accountable care and population health, large provider organizations are looking for new ways to predict diseases in their population, especially for people with diabetes. Although diabetes has been associated with the incidence of obesity, many diabetes patients are not obese. However, we find that just living in a household with one or more obese biologically related family members is a major risk factor for diabetes, even after accounting for all the other traditional risk factors.

Association of the genetic variants of insulin receptor substrate 1 (IRS-1) with type 2 diabetes mellitus in a Saudi population

Type 2 diabetes mellitus (T2DM) is a chronic degenerative disease, phenotypically and genetically heterogeneous, characterized by high levels of glucose and metabolic complications. Insulin receptor substrate 1 (IRS-1) plays a key role in the insulin-stimulated signal transduction pathway. A glycine-to-arginine substitution at codon 972 (G972R) (rs1801278) in the IRS-1 gene has been associated with impaired insulin action. Another SNP rs2943641 in the IRS-1 gene has been found to be associated with T2DM and insulin resistance in genome-wide association studies. The aim of the present study was to evaluate whether rs1801278 and rs2943641 are associated with increased risk of T2DM in the Saudi population. The study included 376 T2DM cases and 380 healthy controls. Genomic DNA was isolated using a commercially available kit supplied by Norgen Biotech Corp. Genotyping was performed by PCR and RFLP analysis. There was a significant difference in the genotypic distribution as well as allelic frequency between the T2DM cases and controls in case of both the polymorphisms for rs1801278 (1.752, 95 % CI 1.002-3.121; p = 0.04), and for rs2943641 (OR = 1.482, 95 % CI 1.176-1.867; p = 0.001). In conclusion, both the (rs1801278 and rs2943641) polymorphisms are associated with T2DM in the Saudi population.

Joint effect of insulin signaling genes on insulin secretion and glucose homeostasis

CONTEXT

Reduced insulin signaling in insulin secreting β-cells causes defective insulin secretion and hyperglycemia in mice.

OBJECTIVE

We investigated whether functional polymorphisms affecting insulin signaling (ie, ENPP1 K121Q, rs1044498; IRS1 G972R, rs1801278; and TRIB3 Q84R, rs2295490) exert a joint effect on insulin secretion and abnormal glucose homeostasis (AGH).

DESIGN

Insulin secretion was evaluated by 1) the disposition index (DI) from an oral glucose tolerance test (OGTT) in 829 individuals; 2) insulin secretion stimulation index (SI) in islets from nondiabetic donors after glucose (n = 92) or glibenclamide (n = 89) stimulation. AGH (including impaired fasting glucose and/or impaired glucose tolerance or type 2 diabetes; T2D) was evaluated in case-control studies from the GENetics of Type 2 Diabetes in Italy and the United States (GENIUS T2D) Consortium (n = 6607).

RESULTS

Genotype risk score, obtained by totaling individual weighted risk allele effects, was associated with the following: 1) DI (P = .005); 2) glucose and glibenclamide SI (P = .046 and P = .009); or 3) AGH (odds ratio 1.08, 95% confidence interval 1.03-1.13; P = .001). We observed an inverse relationship between genetic effect and age at AGH onset, as indicated by a linear correlation between AGH-genotype risk score odds ratios and age-at-diagnosis cutoffs (R(2) = 0.80, P < .001).

CONCLUSIONS

Functional polymorphisms affecting insulin signaling exert a joint effect on both in vivo and in vitro insulin secretion as well as on early-onset AGH. Our data provide further evidence that abnormal insulin signaling reduces β-cell function and impairs glucose homeostasis.

Insulin signaling regulating genes: effect on T2DM and cardiovascular risk

Type 2 diabetes mellitus (T2DM) is a complex disorder that has a heterogeneous genetic and environmental background. In this Review, we discuss the role of relatively infrequent polymorphisms of genes that regulate insulin signaling (including the K121Q polymorphism of ENPP1, the G972R polymorphism of IRS1 and the Q84R polymorphism of TRIB3) in T2DM and other conditions related to insulin resistance. The biological relevance of these three polymorphisms has been very thoroughly characterized both in vitro and in vivo and the available data indicate that they all affect insulin signaling and action as well as insulin secretion. They also affect insulin-mediated regulation of endothelial cell function. In addition, several reports indicate that the effects of all three polymorphisms on the risk of T2DM and cardiovascular diseases related to insulin resistance depend on the clinical features of the individual, including their body weight and age at disease onset. Thus, these polymorphisms might be used to demonstrate how difficult it is to ascertain the contribution of relatively infrequent genetic variants with heterogeneous effects on disease susceptibility. Unraveling the role of such variants might be facilitated by improving disease definition and focusing on specific subsets of patients.

Polymorphisms of insulin receptor substrate 1 and beta3-adrenergic receptor genes in gestational diabetes and normal pregnancy

Gestational diabetes mellitus (GDM) is considered an important risk factor for the development of type 2 diabetes mellitus. We studied possible relations between GDM and both insulin receptor substrate 1 (IRS-1) (Gly972Arg) and beta3-adrenergic receptor (ADRB3 Trp64Arg, beta3-AR) gene mutations, considered potential modifying factors in the etiology of type 2 diabetes mellitus. We evaluated the 2 gene mutations in late gestation in 627 pregnant women, all studied using the glucose challenge test, followed (in positive tests) by the oral glucose tolerance test (100 g, Carpenter and Coustan [J Obstet Gynecol. 1982;144:768-773] criteria) We diagnosed 309 women with GDM, 41 with gestational impaired glucose tolerance and 277 normal pregnant women. Age, family history of diabetes, prepregnancy body mass index, weight gain during pregnancy, plasma glucose levels, hemoglobin A1c, islet autoantibody levels, and insulin treatment during pregnancy were all evaluated. All pregnant women were genotyped for IRS-1 (Gly972Arg) and beta3-AR (ADRB3 Trp64Arg) polymorphisms. The frequency of IRS-1 gene polymorphism was significantly higher in women with GDM than in women with a normal glucose tolerance (NGT) (P = .039), and there was a significant trend (P = .032) in the increasing frequency of mutant allele Arg from NGT > gestational impaired glucose tolerance > GDM. The search for beta3-AR gene polymorphism showed no significant differences between women with GDM and women with NGT. The X-Arg genotype of IRS-1 was significantly associated with a positive family history of diabetes in NGT (P = .006) and neared significance in GDM (P = .057). Moreover, we found that NGT carriers of both polymorphisms had a higher prepregnancy body mass index than carriers of the IRS-1 variant alone (P = .0034), the beta3-AR variant alone (P = .039), or neither (P = .048), suggesting a possible synergistic effect of the 2 gene polymorphisms. These results suggest that the IRS-1 genetic polymorphism is involved in the occurrence of gestational diabetes, as well as type 2 diabetes mellitus.

EIF4A2 is a positional candidate gene at the 3q27 locus linked to type 2 diabetes in French families

One of the most replicated loci influencing type 2 diabetes-related quantitative traits (quantitative trait loci [QTL]) is on chromosome 3q27 and modulates both type 2 diabetes-and metabolic syndrome-associated phenotypes. A QTL for type 2 diabetes age of onset (logarithm of odds [LOD] score = 3.01 at D3S3686, P = 0.0001) was identified in a set of French families. To assess genetic variation underlying both age-of-onset QTL and our previous type 2 diabetes linkage in a 3.87-Mb interval, we explored 36 single nucleotide polymorphisms (SNPs) in two biologically relevant candidate genes for glucose homeostasis, kininogen (KNG1), and eukaryotic translation initiation factor 4alpha2 (EIF4A2). Analysis of 148 families showed significant association of a frequent SNP, rs266714, located 2.47 kb upstream of EIF4A2, with familial type 2 diabetes (family-based association test, P = 0.0008) and early age of onset (P = 0.0008). This SNP also contributes to both age-of-onset QTL (1.13 LOD score decrease P = 0.02) and type 2 diabetes linkage (genotype identical-by-descent sharing test, P = 0.02). However, no association was observed in three independent European diabetic cohorts. EIF4A2 controls specific mRNA translation and protein synthesis rate in pancreatic beta-cells, and our data indicates that EIF4A2 is downregulated by high glucose in rat beta-INS832/13 cells. The potential role of EIF4A2 in glucose homeostasis and its putative contribution to type 2 diabetes in the presence of metabolic stress will require further investigation.

Genetics for targeting disease prevention: diabetes

This article provides an overview of current thinking regarding genetics and diabetes (type 1, type 2, and gestational diabetes mellitus),including a selective look at a few implicated gene variants. This article explores how this information might be applied in current and future clinical practice to (1) predict who is at risk for diabetes and its complications, (2) identify and intervene to prevent or delay the development of diabetes in persons at risk, (3) identify patients with diabetes in an early stage and intervene to prevent later complications,and (4) individualize therapy for patients with diabetes to improve outcomes. The article concludes with some general thoughts about genetics and diabetes prevention in the future.

Strong family history predicts a younger age of onset for subjects diagnosed with type 2 diabetes

AIMS

Age of onset of type 2 diabetes is becoming earlier and with it there is an increase in the development of chronic complications. This study examined the relationship between the strength of family history of diabetes on (i) age of diabetes onset and (ii) prevalence of diabetic complications.

RESEARCH DESIGN AND METHODS

Data on family history of diabetes and age of diabetes onset were prospectively collected on 5193 subjects. Family members were deemed to include grandparents, parents, siblings, aunts/uncles and children. To adjust for family size and to assess effects of pathway to diagnosis, we also contacted a subset of 180 patients selected on the basis of the strength of family histories of diabetes. A full assessment for diabetic complications including retinopathy, neuropathy and renal and macrovascular status was performed for the total cohort.

RESULTS

The more cases of diabetes found in a family, the younger the age of onset of type 2 diabetes. This phenomenon does not appear to be due to patients with strong family history of diabetes being more concerned about the possibility of having diabetes. The effect of strong family history is also evident in many ethnic groups when examined individually, although they differ from each other in their characteristic age of onset of diabetes. Once adjusted for duration of diabetes, strength of family history does not appear to affect metabolic profiles or prevalence of chronic complications.

CONCLUSIONS

There is a strong relationship between the number of affected family members with diabetes and age of developing diabetes. The genetic and environmental factors underlying this phenomenon remain to be elucidated. However, it may be one of the reasons explaining why type 2 diabetes is affecting younger people worldwide.

Young-onset type 2 diabetes families are the major contributors to genetic loci in the Diabetes UK Warren 2 genome scan and identify putative novel loci on chromosomes 8q21, 21q22, and 22q11

A young onset of type 2 diabetes is likely to result, in part, from greater genetic susceptibility. Young-onset families may therefore represent a group in which genes are more easily detectable by linkage. To test this hypothesis, we conducted age at diagnosis (AAD) stratified linkage analyses in the Diabetes UK Warren 2 sibpairs. In the previously published unstratified analysis, evidence for linkage (logarithm of odds [LOD] >1.18) was found at seven loci. The LOD scores at these seven loci were higher in the 245 families with AAD <55 years (L55) compared with the 328 families with AAD >55 years (G55). Five of these seven loci (1q24-25, 5q13, 8p21-22, 8q24.2, and 10q23.2) had LOD scores >1.18 in the L55 subset but only one (8p21-22) did in the G55 subset. Two additional loci (8q21.13 and 21q22.2) showed evidence for linkage in the L55 subset alone. Another locus (22q11) showed evidence for linkage in a subset of families with AAD <45 years. Using a locus-counting approach, the L55 subset had significantly more loci (P approximately 0.01) than expected under the null hypothesis of no linkage across the LOD score range 0.59-3.0. In contrast, the G55 subset contained no more susceptibility loci than that expected by chance. In conclusion, young-onset families provide both disproportionate evidence for linkage to known loci and evidence for additional novel loci. Our data confirm our hypothesis that families segregating young-onset type 2 diabetes represent a more powerful resource for defining susceptibility genes by linkage.

Gly972Arg variant in the insulin receptor substrate-1 gene and association with Type 2 diabetes: a meta-analysis of 27 studies

AIMS/HYPOTHESIS

Several case-control studies have examined the association between the Gly972Arg variant in the IRS-1 gene and Type 2 diabetes, but most had limited power and results could therefore be conflicting.

METHODS

We systematically reviewed the literature by means of a meta-analysis and investigated sources of heterogeneity in results of different studies.

RESULTS

The summary risk ratio, based on 3408 cases and 5419 control cases from 27 studies, was 1.25 (95% CI 1.05-1.48). The results, however, differed according to the type of study, method of verifying non-diabetic status of the control subjects, and age of the case subjects. Population-based studies reported lower odds ratios than hospital-based studies (OR 0.98, 95% CI 0.74-1.30 vs OR 1.43, 95% CI 1.17-1.74). Also, the diagnostic test to exclude diabetes amongst control subjects interacted with the association between the IRS-1 Gly972Arg variant and Type 2 diabetes (p=0.03). Finally, the odds ratio reduced with increasing age ( p=0.03).

CONCLUSION/INTERPRETATION

Overall, carriers of the 972Arg variant of the IRS-1 gene are at a 25% increased risk of having Type 2 diabetes compared with non-carriers. The odds ratios are generally higher in hospital-based studies, including relatively young, symptomatic, cases.