Genetic Determinants of Type 2 Diabetes in Asians

Ethnic differences in risk factors and prevalence of type 2 diabetes in the adult population of the Russian Federation

BACKGROUND: Russia is one of the most multinational states in the world. Identification of ethnic groups with a higher risk of developing DM2, analysis of risk factors for the development of DM2 will allow developing personalized approaches to the prevention and treatment of DM2.

AIMS: To reveal ethnic features of the prevalence of carbohydrate metabolism disorders and risk factors for the development of DM2 in the adult population of the Russian Federation.

MATERIALS AND METHODS. A retrospective analysis of the database of the national epidemiological cross-sectional study NATION was carried out. Depending on the self-specified nationality, on the basis of anthropological characteristics, the following ethnic groups were identified: “Mongoloid population”, “Peoples of the Volga region”, “Peoples of the North Caucasus”, “Peoples of Transcaucasia”, “Russians”. The analysis consisted of several stages and included: analysis of the anthropometric features of the selected groups, taking into account the presence of carbohydrate metabolism disorders (MO); study of the prevalence of violations of the MA in the selected ethnic groups; analysis of ethnic characteristics of risk factors for the development of type 2 diabetes; analysis of the frequency of violations of the MA in various ethnic groups, taking into account the territory of residence. MR disorders were defined as the presence of DM and/or prediabetes. In accordance with the WHO criteria, HbA1c≥6.5% corresponded to the diagnosis of DM, HbA1c values in the range of 5.7%≤HbA1c<6.5% to the diagnosis of prediabetes.

RESULTS: The highest frequency of violations of the MA was observed in the group «Peoples of the Volga region» (31.2%), the lowest in the «Peoples of the North Caucasus» (15.6%). BMI in the group “Peoples of the Volga region” was significantly lower than in the group “Peoples of the North Caucasus. Violations of MR were more often observed in the abdominal nature of obesity, obesity of the 1st stage, age over 45 years in the groups «Mongoloid population» and «Peoples of the Volga region» than in the peoples of the «Northern Caucasus» and «Transcaucasia». The frequency of occurrence of SR violations among representatives of the Volga Peoples group living in their historical territories was higher than among Russians living in the same regions: 32.5% and 24.3% (p<0.001 χ2 criterion), and also higher than in the Russian CFD: 32.5% and 27.4%, respectively, p=0.001 (χ2 test). The prevalence of violations of the MA among the peoples of the North Caucasus was less than among the Russians of the Central Federal District — 13.9% and 27.36%, respectively (p<0.001 χ2 criterion). The prevalence of MR violations among representatives of the “Peoples of the North Caucasus” group living in their historical territories (n=598) was less than among those living in other regions of the Russian Federation (n=164) (13.9% and 21.95%, p= 0.012 criterion χ2).

CONCLUSION: In the present work, for the first time, we analyzed the prevalence of MR disorders in various ethnic groups of the population of the Russian Federation, identified certain ethnic characteristics of DM2 risk factors and their contribution to the development of the disease. The obtained results should be used for planning preventive programs in various regions of the Russian Federation.

Microbiome risk profiles as biomarkers for inflammatory and metabolic disorders

The intestine harbours a complex array of microorganisms collectively known as the gut microbiota. The past two decades have witnessed increasing interest in studying the gut microbiota in health and disease, largely driven by rapid innovation in high-throughput multi-omics technologies. As a result, microbial dysbiosis has been linked to many human pathologies, including type 2 diabetes mellitus and inflammatory bowel disease. Integrated analyses of multi-omics data, including metagenomics and metabolomics along with measurements of host response and cataloguing of bacterial isolates, have identified many bacteria and bacterial products that are correlated with disease. Nevertheless, insight into the mechanisms through which microbes affect intestinal health requires going beyond correlation to causation. Current understanding of the contribution of the gut microbiota to disease causality remains limited, largely owing to the heterogeneity of microbial community structures, interindividual differences in disease evolution and incomplete understanding of the mechanisms that integrate microbiota-derived signals into host signalling pathways. In this Review, we provide a broad insight into the microbiome signatures linked to inflammatory and metabolic disorders, discuss outstanding challenges in this field and propose applications of multi-omics technologies that could lead to an improved mechanistic understanding of microorganism-host interactions.

Comparative epidemiology of gestational diabetes in ethnic Chinese from Shanghai birth cohort and growing up in Singapore towards healthy outcomes cohort

BACKGROUND

Gestational diabetes mellitus (GDM) has been associated with adverse health outcomes for mothers and offspring. Prevalence of GDM differs by country/region due to ethnicity, lifestyle and diagnostic criteria. We compared GDM rates and risk factors in two Asian cohorts using the 1999 WHO and the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria.

METHODS

The Shanghai Birth Cohort (SBC) and the Growing Up in Singapore Towards healthy Outcomes (GUSTO) cohort are prospective birth cohorts. Information on sociodemographic characteristics and medical history were collected from interviewer-administered questionnaires. Participants underwent a 2-h 75-g oral glucose tolerance test at 24-28 weeks gestation. Logistic regressions were performed.

RESULTS

Using the 1999 WHO criteria, the prevalence of GDM was higher in GUSTO (20.8%) compared to SBC (16.6%) (p = 0.046). Family history of hypertension and alcohol consumption were associated with higher odds of GDM in SBC than in GUSTO cohort while obesity was associated with higher odds of GDM in GUSTO. Using the IADPSG criteria, the prevalence of GDM was 14.3% in SBC versus 12.0% in GUSTO. A history of GDM was associated with higher odds of GDM in GUSTO than in SBC, while being overweight, alcohol consumption and family history of diabetes were associated with higher odds of GDM in SBC.

CONCLUSIONS

We observed several differential risk factors of GDM among ethnic Chinese women living in Shanghai and Singapore. These findings might be due to heterogeneity of GDM reflected in diagnostic criteria as well as in unmeasured genetic, lifestyle and environmental factors.

Resistin expression in human monocytes is controlled by two linked promoter SNPs mediating NFKB p50/p50 binding and C-methylation

Resistin is a key cytokine associated with metabolic and inflammatory diseases. Especially in East Asian populations, the expression levels are strongly influenced by genetic polymorphisms. Mechanisms and functional implications of this genetic control are still unknown. By employing reporter assays, EMSA, inhibition studies, bisulphite sequencing, ChIP-Seq and gene-editing we show that the p50/p50 homodimer known to act as repressor for a number of pro-inflammatory genes plays a central role in the genetic regulation of resistin in monocytes along with promoter methylation. In the common RETN haplotype p50/p50 constitutively dampens the expression by binding to the promoter. In an Asian haplotype variant however this interaction is disrupted by the A allele of rs3219175. The SNP is in very close linkage to rs34861192, a CpG SNP, located 280 bp upstream which provides an allele-specific C-methylation site. rs34861192 is located in a 100 bp region found to be methylated in the common but not in the Asian haplotype, resulting in the latter having a higher basal expression, which also associates with elevated histone acetylation (H3K27ac). Genotype associations within cohort data of 200 East Asian individuals revealed significant associations between this haplotype and the plasma levels of factors such as TGF-b, S100B, sRAGE and IL-8 as well as with myeloid DC counts. Thus, the common RETN haplotype is tightly regulated by the epigenetic mechanism linked to p50/p50-binding. This control is lost in the Asian haplotype, which may have evolved to balance the antagonistic RETN effects on pathogen protection vs. metabolic and inflammatory disease induction.

Association of Diabetes With All-Cause and Cause-Specific Mortality in Asia: A Pooled Analysis of More Than 1 Million Participants

IMPORTANCE

Asia is home to the largest diabetic populations in the world. However, limited studies have quantified the association of diabetes with all-cause and cause-specific mortality in Asian populations.

OBJECTIVES

To evaluate the association of diabetes with all-cause and cause-specific mortality in Asia and to investigate potential effect modifications of the diabetes-mortality associations by participants' age, sex, education level, body mass index, and smoking status.

DESIGN, SETTING, AND PARTICIPANTS

This pooled analysis incorporated individual participant data from 22 prospective cohort studies of the Asia Cohort Consortium conducted between 1963 and 2006. A total of 1 002 551 Asian individuals (from mainland China, Japan, South Korea, Singapore, Taiwan, India, and Bangladesh) were followed up for more than 3 years. Cohort-specific hazard ratios and 95% confidence intervals for all-cause and cause-specific mortality were estimated using Cox regression models and then pooled using random-effects meta-analysis. Analysis was conducted between January 10, 2018, and August 31, 2018.

EXPOSURES

Doctor-diagnosed diabetes, age, sex, education level, body mass index, and smoking status.

MAIN OUTCOMES AND MEASURES

All-cause and cause-specific mortality.

RESULTS

Of 1 002 551 participants (518 537 [51.7%] female; median [range] age, 54.0 [30.0-98.0] years), 148 868 deaths were ascertained during a median (range) follow-up of 12.6 (3.0-38.9) years. The overall prevalence of diabetes reported at baseline was 4.8% for men and 3.6% for women. Patients with diabetes had a 1.89-fold risk of all-cause death compared with patients without diabetes (hazard ratio [HR], 1.89; 95% CI, 1.74-2.04), with the highest relative risk of death due to diabetes itself (HR, 22.8; 95% CI, 18.5-28.1), followed by renal disease (HR, 3.08; 95% CI, 2.50-3.78), coronary heart disease (HR, 2.57; 95% CI, 2.19-3.02), and ischemic stroke (HR, 2.15; 95% CI, 1.85-2.51). The adverse diabetes-mortality associations were more evident among women (HR, 2.09; 95% CI, 1.89-2.32) than among men (HR, 1.74; 95% CI, 1.62-1.88) (P for interaction < .001) and more evident among adults aged 30 to 49 years (HR, 2.43; 95% CI, 2.08-2.84) than among adults aged 70 years and older (HR, 1.51; 95% CI, 1.40-1.62) (P for interaction < .001). A similar pattern of association was found between diabetes and cause-specific mortality, with significant variations noted by sex and age.

CONCLUSIONS AND RELEVANCE

This study found that diabetes was associated with increased risk of death from several diseases among Asian populations. Development and implementation of diabetes management programs are urgently needed to reduce the burden of diabetes in Asia.