Genetics of type 2 diabetes in East Asian populations

Identification of genetic loci enriched in obese or lean T2D cases in the Korean population

BACKGROUND

Obesity causes many complex diseases including type 2 diabetes (T2D). Obesity increases the risk of T2D in Europeans, but there are many non-obese (lean) T2D patients in East Asia.

OBJECTIVE

To discover genetic factors enriched in obese or lean T2D patients, we conducted a genome-wide association (GWA) analysis for T2D stratified by BMI in the Korean population.

METHODS

In the discovery stage, 654 and 247 individuals classified as obese (BMI > 25) and lean (BMI < 23) T2D patients, respectively, were compared with 3,842 control subjects for GWA analysis. Several BMI-stratified T2D variants detected in the discovery stage were further tested in the replication stage, which included 402 obese and 220 lean T2D cases, and 3,615 controls.

RESULTS

Meta-analysis combining the discovery and replication stages detected two variants with genome-wide significance: rs2356138 [P = 2.8 × 10-8, OR = 2.06 (1.59-2.65)] in obese T2D subjects and rs9295478 [P = 2.5 × 10-9, OR = 1.61 (1.38-1.88)] in lean ones. The SNP rs9295478 is located in CDKAL1, a well-known T2D gene previously identified in several GWA studies. Meanwhile, the SNP rs2356138 is a previously unknown variant located in PKP4.

CONCLUSION

We discovered genetic loci enriched in obese or lean T2D patients in the Korean population. Our findings should facilitate more effective control of T2D in Koreans.

Styrene and ethylbenzene exposure and type 2 diabetes mellitus: A longitudinal gene-environment interaction study

Styrene and ethylbenzene (S/EB) are identified as hazardous air contaminants that raise significant concerns. The association between S/EB exposure and the incidence of type 2 diabetes mellitus (T2DM), and the interaction between genes and environment, remains poorly understood. Our study consisted of 2219 Chinese adults who were part of the Wuhan-Zhuhai cohort. A follow-up assessment was conducted after six years. Exposure to S/EB was quantified by determining the concentrations of urinary biomarkers of exposure to S/EB (UBE-S/EB; urinary phenylglyoxylic acid level plus urinary mandelic acid level). Logistic regression models were constructed to investigate the relations of UBE-S/EB and genetic risk score (GRS) with T2DM prevalence and incidence. The interaction effects of UBE-S/EB and GRS on T2DM were investigated on multiplicative and additive scales. UBE-S/EB was dose-dependently and positively related to T2DM prevalence and incidence. Participants with high levels of UBE-S/EB [relative risk (RR) = 1.930, 95% confidence interval (CI): 1.157-3.309] or GRS (1.943, 1.110-3.462) demonstrated the highest risk of incident T2DM, in comparison to those with low levels of UBE-S/EB or GRS. Significant additive interaction between UBE-S/EB and GRS on T2DM incidence was discovered with relative excess risk due to interaction (95% CI) of 0.178 (0.065-0.292). The RR (95% CI) of T2DM incidence was 2.602 (1.238-6.140) for individuals with high UBE-S/EB and high GRS, compared to those with low UBE-S/EB and low GRS. This study presented the initial evidence that S/EB exposure was significantly related to increased risk of T2DM incidence, and the relationship was interactively aggravated by genetic predisposition.

An Insight into Vital Genes Responsible for β-cell Formation

The regulation of glucose homeostasis and insulin secretion by pancreatic β-cells, when disturbed, will result in diabetes mellitus. Replacement of dysfunctional or lost β-cells with fully functional ones can tackle the problem of β-cell generation in diabetes mellitus. Various pancreatic-specific genes are expressed during different stages of development, which have essential roles in pancreatogenesis and β-cell formation. These factors play a critical role in cellular-based studies like transdifferentiation or de-differentiation of somatic cells to multipotent or pluripotent stem cells and their differentiation into functional β-cells. This work gives an overview of crucial transcription factors expressed during various stages of pancreas development and their role in β-cell specification. In addition, it also provides a perspective on the underlying molecular mechanisms.

Alkaline-sensitive two-pore domain potassium channels form functional heteromers in pancreatic β-cells

Two-pore domain K⁺ channels (K_2P channels), active as dimers, produce inhibitory currents regulated by a variety of stimuli. Among them, TWIK1-related alkalinization-activated K⁺ channel 1 (TALK1), TWIK1-related alkalinization-activated K⁺ channel 2 (TALK2), and TWIK1-related acid-sensitive K⁺ channel 2 (TASK2) form a subfamily of structurally related K_2P channels stimulated by extracellular alkalosis. The human genes encoding these proteins are clustered at chromosomal region 6p21 and coexpressed in multiple tissues, including the pancreas. The question whether these channels form functional heteromers remained open. By analyzing single-cell transcriptomic data, we show that these channels are coexpressed in insulin-secreting pancreatic β-cells. Using in situ proximity ligation assay and electrophysiology, we show that they form functional heterodimers both upon heterologous expression and under native conditions in human pancreatic β-cells. We demonstrate that heteromerization of TALK2 with TALK1 or with TASK2 endows TALK2 with sensitivity to extracellular alkalosis in the physiological range. We further show that the association of TASK2 with TALK1 and TALK2 increases their unitary conductance. These results provide a new example of heteromerization in the K_2P channel family expanding the range of the potential physiological and pathophysiological roles of TALK1/TALK2/TASK2 channels, not only in insulin-secreting cells but also in the many other tissues in which they are coexpressed.

Association of alcohol drinking with incident type 2 diabetes and pre-diabetes: The Guangzhou Biobank Cohort Study

AIMS

We examined associations of baseline alcohol drinking with incident type 2 diabetes (T2D) or impaired fasting glucose (IFG), and explore whether the associations were modified by genetic polymorphisms of aldehyde dehydrogenase-2 (ALDH2) and alcohol dehydrogenase-1B (ADH1B).

MATERIALS AND METHODS

All participants were aged 50+ (mean = 60.45; standard deviation = 6.88) years. Information of alcohol consumption was collected at baseline from 2003 to 2008. Incident T2D was defined as fasting glucose ≥7.0 mmol/L or post-load glucose ≥11.1 mmol/L at follow-up examination (2008-2012), self-reported T2D and/or initiation of hypoglycaemia medication or insulin during follow-up. Impaired fasting glucose was defined as fasting glucose ≥5.6 mmol/L and <7 mmol/L.

RESULTS

Of 15,716 participants without diabetes and 11,232 participants without diabetes and IFG at baseline, 1624 (10.33%) developed incident T2D and 1004 (8.94%) developed incident IFG during an average 4 years of follow-up. After multivariable adjustments, compared with never drinking, occasional or moderate alcohol drinking was not associated with risk of incident hyperglycaemia (T2D + IFG) (odds ratio (OR) = 1.10, 95% confidence interval (CI) 0.95-1.27, and 0.90 (0.69-1.18), respectively), whereas heavy alcohol drinking was associated with a higher risk of incident hyperglycaemia (T2D + IFG) (OR = 1.82, 95% CI 1.24-2.68). No interactions of sex, overweight/obesity and genetic polymorphisms of ADH1B/ALDH2 genes with alcohol drinking on incident T2D and/or IFG were found (P for interaction from 0.12 to 0.85).

CONCLUSIONS

Our results support a detrimental effect of heavy alcohol use on IFG and T2D. No protective effect was found for those carrying lower risk alleles for ADH1B/ALDH2 genes.

Genetic susceptibility, family history of diabetes and healthy lifestyle factors in relation to diabetes: A gene-environment interaction analysis in Chinese adults

AIMS/INTRODUCTION

To analyze the associations and interactions of the genetic susceptibility and family history of diabetes with lifestyle factors in relation to diabetes among Chinese adults.

MATERIALS AND METHODS

We constructed a genetic risk score of 34 single-nucleotide polymorphisms in 11,596 participants from Songnan and Youyi communities, Baoshan District, Shanghai, China. We determined a healthy lifestyle by a normal body mass index (<24 kg/m2 ), adequate fruit and vegetable intake (≥4.5 cups/day), never smoked or quit smoking >1 year prior, sufficient physical activity (≥600 metabolic equivalent minutes per week), and a sleep duration of ≥6 to ≤8 h/day. Logistic regression models were used to examine the associations and interactions between heritability and lifestyle on diabetes.

RESULTS

A healthier lifestyle was associated with a lower prevalence of diabetes within any heritable risk groups categorized by the genetic risk score and family history of diabetes. In the combined communities, the odds ratio (95% confidence interval) for diabetes associated with each additional healthy lifestyle factor was 0.83 (0.77-0.89) among participants with a low genetic risk score and 0.86 (0.81-0.91) among participants with a high genetic risk score (Pinteraction  = 0.66). Similar interaction patterns of family history (Pinteraction  = 0.15) and the combination of family history and the genetic risk score with healthy lifestyle (Pinteraction  = 0.55) on diabetes were observed.

CONCLUSIONS

A healthier lifestyle was associated with a significantly lower prevalence of diabetes regardless of heritable risk groups, highlighting the importance of adhering to a healthy lifestyle for diabetes prevention among the entire population.

Fruit intake, genetic risk and type 2 diabetes: a population-based gene-diet interaction analysis

PURPOSE

Whether the association between fruit and type 2 diabetes (T2D) is modified by the genetic predisposition of T2D was yet elucidated. The current study is meant to examine the gene-dietary fruit intake interactions in the risk of T2D and related glycemic traits.

METHODS

We performed a cross-sectional study in 11,657 participants aged ≥ 40 years from a community-based population in Shanghai, China. Fruit intake information was collected by a validated food frequency questionnaire by asking the frequency of consumption of typical food items over the previous 12 months. T2D-genetic risk score (GRS) was constructed by 34 well established T2D common variants in East Asians. The risk of T2D, fasting, 2 h-postprandial plasma glucose, and glycated hemoglobin A1c associated with T2D-GRS and each individual single nucleotide polymorphisms (SNPs) were tested.

RESULTS

The risk of T2D associated with each 1-point of T2D-GRS was gradually decreased from the lower fruit intake level (< 1 times/week) [the odds ratio (OR) and 95% confidence interval (CI) was 1.10 (1.07-1.13)], to higher levels (1-3 and > 3 times/week) [the corresponding ORs and 95% CIs were 1.08 (1.05-1.10) and 1.07 (1.05-1.08); P for interaction = 0.04]. Analyses for associations with fasting, 2 h-postprandial plasma glucose and glycated hemoglobin A1c demonstrated consistent tendencies (all P for interaction ≤ 0.03). The inverse associations of fruit intake with risk of T2D and glucose traits were more prominent in the higher T2D-GRS tertile.

CONCLUSIONS

Fruit intakes interact with the genetic predisposition of T2D on the risk of diabetes and related glucose metabolic traits. Fruit intake alleviates the association between genetic predisposition of T2D and the risk of diabetes; the association of fruit intake with a lower risk of diabetes was more prominent in population with a stronger genetic predisposition of T2D.

Early-life exposure to the Chinese famine, genetic susceptibility and the risk of type 2 diabetes in adulthood

AIMS/HYPOTHESIS

Early famine exposure has been related to the development of type 2 diabetes; however, little is known about whether the genetic background modifies this association. We aimed to investigate the joint effects of famine exposure at different stages of early life and genetic susceptibility on diabetes risk in adulthood.

METHODS

The study included 8350 participants from the Survey on Prevalence in East China for Metabolic Diseases and Risk Factors (SPECT-China) who were born around the time of the Chinese Great Famine. We determined famine exposure subgroups according to the birth year as nonexposed (1963-1974), fetal-exposed (1959-1962), childhood-exposed (1949-1958), and adolescence-exposed (1941-1948). We developed a genetic risk score of 21 variants previously associated with type 2 diabetes in East Asians. Hierarchical logistic models were used to examine the association of famine exposure and genetic risk with diabetes.

RESULTS

The age-standardised prevalence of diabetes in nonexposed, fetal-exposed, childhood-exposed and adolescence-exposed subgroups was 13.0%, 18.2%, 15.1% and 13.2%, respectively. Compared with nonexposed participants, fetal-exposed participants showed an increased risk of diabetes in adulthood (OR 1.47; 95% CI 1.13, 1.93). A higher genetic risk score was associated with an increased risk of diabetes (OR 1.23; 95% CI 1.15, 1.31 per SD increment). The association between famine exposure and diabetes was consistent across genetic risk strata (all p for interaction >0.05). When considered jointly, fetal- or childhood-exposed participants at high genetic risk (highest tertile of genetic risk score) had 2.60-fold (95% CI 1.71, 3.93) and 1.95-fold (95% CI 1.24, 3.05) higher risks of diabetes, respectively, compared with nonexposed participants at low genetic risk (lowest tertile).

CONCLUSIONS/INTERPRETATIONS

Prenatal exposure to famine was associated with an increased risk of type 2 diabetes in Chinese adults independent of genetic risk score using 21 variants common in the East Asian population. Famine exposure and genetic susceptibility may exhibit an additive effect on diabetes development.

Ten SNPs May Affect Type 2 Diabetes Risk in Interaction with Prenatal Exposure to Chinese Famine

Increasing studies have demonstrated that gene and famine may interact on type 2 diabetes risk. The data derived from the cross-sectional 2010-2012 China National Nutrition and Health Survey (CNNHS) was examined to explore whether gene and famine interacted to influence type 2 diabetes risk. In total, 2216 subjects were involved. The subjects born in 1960 and 1961 were selected as the famine-exposed group, whereas subjects born in 1963 were selected as the unexposed group. A Mass Array system was used to detect the genotypes of 50 related single-nucleotide polymorphisms (SNPs). Interactions were found between prenatal exposure to famine and ten SNPs (rs10401969, rs10886471, rs10946398, rs1470579, rs2796441, rs340874, rs3794991, rs5015480, rs7961581, and rs9470794) on type 2 diabetes risk after adjustments. The stratified results showed that famine exposure exacerbated the effect of CILP2-rs10401969 to fasting serum insulin (FINS), GRK5-rs10886471 to fasting plasma glucose (FPG) and FINS, IGF2BP2-rs1470579 to FINS, TLE1-rs2796441 to impaired fasting glucose (IFG), PROX1-rs340874 to impaired glucose tolerance (IGT), GATAD2A-rs3794991 to FINS, TSPAN8/LGR5-rs7961581 to FPG, and ZFAND3-rs9470794 to IGT and FINS. Famine exposure weakened the effect of CDKAL1-rs10946398 to type 2 diabetes. Famine exposure weakened the effect of HHEX-rs5015480 to IFG, but exacerbated the effect of HHEX-rs5015480 to FINS. The present study suggests that ten SNPs may affect type 2 diabetes risk in interaction with prenatal exposure to Chinese famine.

KCNQ1 common genetic variant and type 2 diabetes mellitus risk

Background

Type 2 diabetes mellitus (T2DM) is a multifactorial trait that both environmental and genetic factors contribute to its pathogenesis. The most common single nucleotide polymorphism (SNP) of the potassium voltage-gated channel subfamily Q member 1 (KCNQ1) gene, rs2237892, is highly associated with the risk of T2DM. The aim of the present study was to examine any association between KCNQ1 gene rs2237892 variant and risk of T2DM in a group of Iranian patients.

Methods

Genotyping was carried out in 100 type 2 diabetic patients and 100 non-diabetic subjects using the Sanger sequencing method.

Results

The CC genotype caused more than 30% reduction in the risk of T2DM in compared with CT. Nonetheless, this association was not statistically significant and this variant had no protective effect for T2DM. A significant difference was not found in genotypes (CC, CT, and TT) and alleles (C and T) frequency of KCNQ1 rs2237892 SNP between T2DM and control groups (P = 0.475 and P = 0.470, respectively).

Conclusions

Our investigations did not show enough evidence for the presence of an association between KCNQ1 gene rs2237892 polymorphism and risk of T2DM among a group of Iranian patients.

Efficacy and safety of ertugliflozin in East/Southeast Asian patients with type 2 diabetes mellitus

AIM

Post-hoc analysis of the efficacy and safety of ertugliflozin in East/Southeast (E/SE) Asian patients with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

Efficacy evaluations used data from randomized, double-blind, phase 3 studies: a pool of two 26-week placebo-controlled studies and one 52-week active-comparator (glimepiride) study. Least squares mean change from baseline was calculated for HbA1c, fasting plasma glucose (FPG), body weight (BW) and systolic blood pressure (SBP). Safety evaluation included overall and prespecified adverse events based on pooled data (broad pool) from seven phase 3 studies (including studies in the efficacy analysis).

RESULTS

Among 161 E/SE Asian patients in the placebo pool (ertugliflozin, n = 106), ertugliflozin reduced HbA1c, FPG, BW and SBP from baseline at week 26. The placebo-adjusted changes from baseline for ertugliflozin 5 and 15 mg were: HbA1c, -0.9% and -1.0%; BW, -2.1 and -1.9 kg; and SBP, -3.3 and -3.5 mmHg, respectively. Among 174 E/SE Asian patients in the active-comparator study (ertugliflozin, n = 118), HbA1c changes from baseline at week 52 were -0.6%, -0.6% and -0.7% for ertugliflozin 5 mg, 15 mg and glimepiride, respectively. Ertugliflozin 5 and 15 mg reduced BW from baseline by -4.3 and -4.1 kg, respectively, and SBP by -7.4 and -9.3 mmHg, respectively, compared with glimepiride. Safety findings were generally consistent with overall ertugliflozin safety data published to date.

CONCLUSIONS

Treatment with ertugliflozin was associated with reductions in HbA1c, FPG, BW and SBP, and was generally well tolerated in E/SE Asian patients with T2DM. ClinicalTrials.gov identifier: NCT01986855, NCT01999218, NCT01958671, NCT02099110, NCT02036515, NCT02033889, NCT02226003.

Association of Genetic Variants of KCNJ11 and KCNQ1 Genes with Risk of Type 2 Diabetes Mellitus (T2DM) in the Indian Population: A Case-Control Study

Type 2 diabetes mellitus (T2DM) is a polygenic metabolic disease described by hyperglycemia, which is caused by insulin resistance or reduced insulin secretion. The interaction between various genetic variants and environmental factors triggers T2DM. The aim of this study was to find risk associated with genetic variants rs5210 and rs2237895 of KCNJ11 and KCNQ1 genes, respectively, in the development of T2DM in the Indian population. A total number of 300 cases of T2DM and 100 control samples were studied to find the polymorphism in KCNJ11 and KCNQ1 through PCR-RFLP. The genotype and allele frequencies in T2DM cases were significantly different compared to the control population. KCNJ11 rs5210 and KCNQ1 rs2237895 variants were found to be significantly associated with risk of T2DM in dominant (KCNJ11: OR, 2.07; 95% CI, 1.30-3.27; p - 0.001; KCNQ1: OR, 2.33; 95% CI, 1.46-3.70; p - 0.0003) and codominant models (KCNJ11: OR, 1.76; 95% CI, 1.09-2.84; p - 0.020; KCNQ1: OR, 1.85; 95% CI, 1.16-2.95; p - 0.009). We also compared clinicopathological characteristics between cases and control and observed a significant difference in all the parameters except HDL, gender, and family history. In this study, clinicopathological data with a carrier of a variant allele of both KCNJ11 and KCNQ1 genes were also analysed, and a significant association was found between the carrier of a variant allele with gender and PPG in KCNJ11 and with triglyceride in KCNQ1. We confirm the significant association of KCNJ11 (rs5210) and KCNQ1 (rs2237895) gene polymorphism with T2DM, indicating the role of these variants in developing risk for T2DM in Indian population.

The Association Between Femoral Artery Intima-Media Thickness and Serum Glucagon-Like Peptide-1 Levels Among Newly Diagnosed Patients with Type 2 Diabetes Mellitus

INTRODUCTION

Endothelium dysfunction and decrease of incretin effects occur early in type 2 diabetes mellitus and these changes contribute to diabetic cardiovascular complications such as atherosclerosis, thick intima-media, coronary, and peripheral arterial diseases. In patients with diabetes, the femoral artery is a site of a high incidence of injury in peripheral vascular diseases, and atherosclerotic changes may appear earlier in the femoral artery compared to the carotid artery. This study was conducted to determine the prevalence of increased femoral artery intima-media thickness (IMT) and atherosclerotic plaque and their correlation with serum glucagon-like peptide-1 (GLP-1) levels in newly-diagnosed patients with type 2 diabetes mellitus.

MATERIALS AND METHODS

A cross-sectional study was conducted on 332 patients with nT2D in the National Endocrinology Hospital, Vietnam from January 2015 to May 2018. IMT was measured by Doppler ultrasound and GLP-1 by enzyme-linked immunosorbent assay (ELISA). All data were analyzed with SPSS version 26 for Windows (SPSS Inc, Chicago, IL).

RESULTS

Prevalence of thick femoral artery IMT and atherosclerotic plaque was 38.2 and 22.3%, respectively. There was a relationship between IMT and age, waist to hip ratio (WHR), systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting GLP-1, high sensitive CRP (hsCRP) and 24-hour microalbuminuria secretion (24-h MAUS). The fasting serum GLP-1 (fGLP-1) levels were reduced significantly in patients with thickness and atherosclerosis femoral artery (p = 0.001). After adjusting with other related factors, namely, DBP and estimated glomerular filtration rate (eGFR), whilst hsCRP and 24-h MAUS showed a significantly positive correlation to IMT (Standardized B and p of 0.242, 0.004 and 0.178, 0.043, respectively), fGLP-1 showed a significantly negative correlation to IMT (Standardized B = -0.288, p = 0.001).

CONCLUSION

Among n2TD, the percentage for femoral artery thick IMT and atherosclerosis was 38.2% and 22.3% respectively, and serum GLP-1 was negatively correlated with thick IMT and atherosclerosis.

Effects of variants of 50 genes on diabetes risk among the Chinese population born in the early 1960s

BACKGROUND

Genome-wide association studies have identified loci that significantly increase diabetes risk. This study explored the genetic susceptibility in relation to diabetes risk in adulthood among a Chinese population born in the early 1960s.

METHODS

In all, 2129 subjects (833 males, 1296 females) were selected from the cross-sectional 2010 to 2012 China National Nutrition and Health Survey. Fifty diabetes-related single nucleotide polymorphisms (SNPs) were detected. Two diabetes genetic risk scores (GRSs) based on the 50 diabetes-predisposing variants were developed to examine the association of these SNPs with diabetes risk.

RESULTS

Associations were found between diabetes risk and SNPs in the MTNR1B (rs10830963), KLHDC5 (rs10842994), GRK5 (rs10886471), cyclindependentkinase 5 regulatory subunit associated protein 1 (rs10946398), adaptorrelated protein complex 3 subunit sigma 2 (rs2028299), diacylglycerol kinase beta/transmembrane protein 195 (rs2191349), SREBF chaperone (rs4858889), ankyrin1 (rs516946), RAS guanyl releasing protein 1 (rs7403531), and zinc finger AN1-type containing 3 (rs9470794) genes. As a continuous variable, with a 1-point increase in the GRS or weighted (w) GRS, fasting plasma glucose (FPG) increased 0.045 and 0.044 mM, respectively (P < 0.001 for both), after adjusting for confounders. Both GRS and wGRS showed an association with diabetes, with a multivariable-adjusted odds ratio (95% confidence interval) of 1.09 (1.00-1.19) and 1.12 (1.03-1.22), respectively, among all subjects. No significant associations were found between the GRS or wGRS and impaired fasting glucose or impaired glucose tolerance.

CONCLUSIONS

The data suggest the association of 10 SNPs and the GRS or wGRS with diabetes risk. Genetic susceptibility to diabetes may synergistically affect the risk of diabetes in adulthood.

Genetic predisposition to type 2 diabetes is associated with severity of coronary artery disease in patients with acute coronary syndromes

Background

Accumulating evidence has shown that type 2 diabetes (T2D) and coronary artery disease (CAD) may stem from a ‘common soil’. The aim of our study was to examine the association between genetic predisposition to T2D and the risk of severe CAD among patients with acute coronary syndromes (ACS) undergoing angiography.

Methods

The current case–control study included 1414 ACS patients with at least one major epicardial vessel stenosis > 50% enrolled in the ACS Genetic Study. The severity of CAD was quantified by the number of coronary arteries involved. Genetic risk score (GRS) was calculated using 41 common variants that robustly associated with increased risk of T2D in East Asians. Logistic regression models were used to estimate the association between GRS and the severity of CAD.

Results

In the age-, sex- and BMI-adjusted model, each additional risk allele was associated with a 6% increased risk of multi-vessel disease (OR = 1.06, 95% CI 1.02–1.09). The OR was 1.43 (95% CI 1.08–1.89) for the risk of severe CAD when comparing the extreme tertiles of T2D-GRS. The association was not reduced after further adjustment for conventional cardiovascular risk factors. Additional adjustment for T2D status in our regression model attenuated the association by approximately one quarter. In subgroup analysis, the strengths of the associations between GRS and the severity of CAD were broadly similar in terms of baseline demographic information and disease characteristics.

Conclusions

Our data indicated that genetic predisposition to T2D is associated with elevated risk of severe CAD. This association revealed a possible causal relationship and is partially mediated through diabetic status.

The Burmese cat as a genetic model of type 2 diabetes in humans

The recent extension of genetic tools to the domestic cat, together with the serendipitous consequences of selective breeding, have been essential to the study of the genetic diseases that affect them. Cats are increasingly presented for veterinary surveillance and share many of human's heritable diseases, allowing them to serve as natural models of these conditions. Feline diabetes mellitus is a common condition in domestic cats that bears close pathological and clinical resemblance to type 2 diabetes in humans, including pancreatic β-cell dysfunction and peripheral insulin resistance. In Australia, New Zealand and Europe, diabetes mellitus is almost four times more common in cats of the Burmese breed than in other breeds. This geographically based breed predisposition parallels familial and population clustering of type 2 diabetes in humans. As a genetically isolated population, the Australian Burmese breed provides a spontaneous, naturally occurring genetic model of type 2 diabetes. Genetically isolated populations typically exhibit extended linkage disequilibrium and increased opportunity for deleterious variants to reach high frequencies over many generations due to genetic drift. Studying complex diseases in such populations allows for tighter control of confounding factors including environmental heterogeneity, allelic frequencies and population stratification. The homogeneous genetic background of Australian Burmese cats may provide a unique opportunity to either refine genetic signals previously associated with type 2 diabetes or identify new risk factors for this disease.

Vitamin D, prediabetes and type 2 diabetes: bidirectional Mendelian randomization analysis

BACKGROUND

Vitamin D deficiency is associated with glycemic dysregulation in many observational studies. However, the causality between them has not been fully established, especially in Asian origin. We used bidirectional Mendelian randomization (MR) analysis to explore the causal relationship between 25-hydroxyvitamin D [25(OH)D] and glycemic status and indices.

METHODS

Participants were included from a survey in East China from 2014 to 2016 (10,338 and 10,655 participants having diabetes and vitamin D-related genotyping information). We calculated weighted genetic risk scores (GRS) as the instrumental variables for 25(OH)D concentration and diabetes based on related single nucleotide polymorphisms. Diagnosis of type 2 diabetes and prediabetes was based on American Diabetes Association criteria.

RESULTS

The MR-derived odds ratios of genetically determined 25(OH)D for risk of type 2 diabetes (1565/10655) and prediabetes (3915/10655) was 0.985 (95% CI 0.940, 1.032) and 0.982 (95% CI 0.948, 1.016), respectively. The MR-derived estimates for fasting plasma glucose and HbA_1c were also not significant. Moreover, the MR-derived regression coefficients of genetically determined diabetes and prediabetes for 25(OH)D was 0.448 (95% CI - 0.395, 1.291) and 1.303 (95% CI - 1.210, 3.816).

CONCLUSIONS

Our results support the conclusion that there is no causal association between vitamin D and type 2 diabetes and prediabetes using a bidirectional MR approach in a Chinese population.

Alcohol consumption and diabetes risk in a Chinese population: a Mendelian randomization analysis

AIM

To assess the causality between alcohol intake, diabetes risk and related traits.

DESIGN

Mendelian randomization (MR) study. Subgroup analysis, standard instrumental variable analysis and local average treatment effect (LATE) methods were applied to assess linear and non-linear causality.

SETTING

China.

PARTICIPANTS

A total of 4536 participants, including 721 diabetes cases.

FINDINGS

Carriage of an ALDH2 rs671 A allele reduced alcohol consumption by 44.63% [95% confidence interval (CI) = -49.44%, -39.37%]. In males, additional carriage of an A allele was significantly connected to decreased diabetes risk for the overall population [odds ratio (OR) = 0.716, 95% CI = 0.567-0.904, P = 0.005] or moderate drinkers (OR = 0.564, 95% CI = 0.355-0.894, P = 0.015). In instrumental variable (IV) analysis, increasing alcohol consumption by 1.7-fold was associated with an incidence-rate ratio of 1.32 (95% CI = 1.06-1.67, P = 0.014) for diabetes risk, and elevated alcohol intake was causally connected to natural log-transformed fasting, 2-hour post-load plasma glucose (β = 0.036, 95% CI = 0.018-0.054; β = 0.072, 95% CI = 0.035-0.108) and insulin resistance [homeostatic model assessment for IR (HOMA-IR] (β = 0.104, 95% CI = 0.039-0.169), but was not associated with beta-cell function (HOMA-beta). In addition, the LATE method did not identify significant U-shaped causality between alcohol consumption and diabetes-related traits. In females, the effects of alcohol intake on all the outcomes were non-significant.

CONCLUSION

Among men in China, higher alcohol intake appears to be causally associated with increased diabetes risk and worsened related traits, even for moderate drinkers. This study found no significant U-shaped causality between alcohol consumption and diabetes-related traits.

ADIPOQ, KCNJ11 and TCF7L2 polymorphisms in type 2 diabetes in Kyrgyz population: A case-control study

The aim of this study was to ascertain the polymorphic markers profile of ADIPOQ,KCNJ11 and TCF7L2 genes in Kyrgyz population and to analyze the association of polymorphic markers and combinations of ADIPOQ gene's G276T locus, KCNJ11 gene's Glu23Lys locus and TCF7L2 gene's VS3C>T locus with type two diabetes (T2D) in Kyrgyz population. In this case‐control study, 114 T2D patients 109 non‐diabetic participants were genotyped using polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP). Two individual polymorphisms (ADIPOQ rs1501299, KCNJ11 rs5219) were found to be associated with T2D. We found two (Lys23Lys/CC and Glu23Lys/CT) of the overall nine combinations, which were more prevalent in T2D group compared to controls (χ² = 4.21, P = 0.04). Lys23Lys/CC combination was associated with a 2.65‐fold increased likelihood of T2D (OR = 2.65, 95% CI 1.12‐6.28), whereas the Glu23Lys/CT combination also increased such likelihood (OR = 3.88, 95% CI 1.27‐11.91). This study demonstrated some association of 276T allele and ADIPOQ gene G276T heterozygous genotype as well as KCNJ11 gene 23Lys allele with T2D in ethnic Kyrgyz, but study results should be interpreted with caution because of the limited statistical power.

Comparison of Placebo Effect between Asian and Caucasian Type 2 Diabetic Patients: A Meta-Analysis

Background:

Placebo was defined as any therapy that is used for its nonspecific psychological and physiologic effect but has no specific pharmacologic impact on the condition being treated. Besides medication therapies, studies have found that the optimal dietary approach as well as physical activity and education are useful to control hyperglycemia in patients with type 2 diabetes (T2DM). The aim of this study was to evaluate the placebo effects of antidiabetic therapies in Asian and Caucasian T2DM patients and make a comparison between the two ethnicities.

Methods:

A search using the MEDLINE database, EMBASE, and Cochrane Database was performed, from when recording began until December 2016. The main concepts searched in English were sulfonylurea (SU); alpha glucosidase inhibitors (AGI); metformin (MET); thiazolidinediones (TZD); dipeptidyl peptidase-4 inhibitors (DPP-4i); sodium-glucose cotransporter 2 inhibitors (SGLT2i); glucagon-like peptide-1 receptor agonist (GLP-1RA); type 2 diabetes (T2DM); placebo controlled; and randomized controlled trials. Using the Cochrane instrument, we evaluated the adequacy of randomization, allocation concealment procedures, and blinding.

Results:

This study included 63 studies with a total of 7096 Asian patients involved and 262 studies with a total of 27,477 Caucasian patients involved. In Caucasian population, the use of placebo led to significant reductions of glycosylated hemoglobin (HbA1c), −0.683% (P = 0.008) in SU monotherapy treatment, −0.193% (P = 0.001) in DPP-4i treatment, and −0.230% (P < 0.001) in SGLT2i treatment, respectively. In Asian population, the use of placebo resulted in significant decreases of HbA1c, −0.162% (P = 0.012) in DPP-4i treatment and −0.269% (P = 0.028) in GLP-1RA add-on therapy, respectively. The placebo also significantly reduced body weight. In Caucasian population, placebo use resulted in 0.833 kg (P = 0.006) weight loss by SU treatment and 0.953 kg (P = 0.006) weight loss by GLP-1RA treatment. In Asian population, the placebo led to a weight change of 0.612 kg (P < 0.001) by GLP-1RA analog treatment. The changes of HbA1c and weight due to the placebo effect in other treatments were not significant in both Asian and Caucasian population. Comparisons of the placebo effect on HbA1c change and weight change in each treatment group indicated that no significant difference was found between Asian and Caucasian population.

Conclusions:

The overall differences of the placebo effect on HbA1c changes as well as on body weight changes were not significant between Asian and Caucasian T2DM patients. The placebo effect on HbA1c changes and weight changes was not associated with baseline age, gender, baseline body mass index, baseline HbA1c, duration of diabetes, or study duration.

No disparity of the efficacy and all-cause mortality between Asian and non-Asian type 2 diabetes patients with sodium-glucose cotransporter 2 inhibitors treatment: A meta-analysis

AIMS/INTRODUCTION

To evaluate whether there is disparity of the efficacy and all-cause mortality and other adverse effects between Asian and non-Asian patients with sodium-glucose cotransporter 2 (SGLT2) inhibitors treatment.

MATERIALS AND METHODS

Randomized clinical trials publicly available before January 2017, comparing SGLT2 inhibitors treatment with a placebo in type 2 diabetes patients were identified. The association between treatment and outcomes was estimated by computing the weighted mean difference for glycated hemoglobin level, blood pressure level, lipid profile levels and bodyweight, and the odds ratios for adverse events.

RESULTS

A total of 17 trials with Asian patients were included and 39 trials with non-Asian patients were included. Comparison of the glycated hemoglobin decreases corrected by a placebo between Asian and non-Asian patients showed that there was a non-significant difference of 0.05% between groups (P > 0.05). Comparisons of the bodyweight changes and blood pressure changes corrected by a placebo between Asian and non-Asian patients did not show a significant difference between groups (P > 0.05). The risk of all-cause mortality was not increased when compared with a placebo both in Asian and non-Asian populations, and the risk of genital infection in Asian and non-Asian populations were both significant increased.

CONCLUSIONS

Overall, according to the present meta-analysis, comparison of the efficacy in SGLT2 inhibitors treatment between Asian and non-Asian type 2 diabetes patients showed no significant difference in glycated hemoglobin reduction and bodyweight reduction. Furthermore, no disparity was found in the risk of all-cause mortality or hypoglycemia in SGLT2 inhibitors treatment between Asian and non-Asian patients.

Type 2 Diabetes and Adiposity Induce Different Lipid Profile Disorders: A Mendelian Randomization Analysis

CONTEXT

Type 2 diabetes and obesity often coexist, so it is difficult to judge whether diabetes or obesity induce certain types of hyperlipidemia due to mutual confounds and reverse causation. We used Mendelian randomization analyses to explore the causal relationships of diabetes and adiposity with lipid profiles.

DESIGN, SETTING, AND MAIN OUTCOME MEASURES

From 23 sites in East China, 9798 participants were enrolled during 2014 to 2016. We calculated two weighted genetic risk scores as instrumental variables for type 2 diabetes and body mass index (BMI). These scores were used to measure the causal relationships of diabetes and BMI with lipid profiles that included total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TGs).

RESULTS

The causal regression coefficients (βIV) of genetically determined diabetes for the total cholesterol, LDL-C, and log10TG were 0.130 [95% confidence interval (CI): 0.020, 0.240; P = 0.014], 0.125 (96% CI: 0.041, 0.209; P = 0.001), and 0.019 (95% CI: -0.001, 0.039; P = 0.055), respectively. The βIV for HDL-C was -0.008 (95% CI: -0.032. 0.016), which was not significant (P = 0.699). The causal regression coefficients of a genetically determined 10 kg/m2 increase in BMI for HDL-C and log10TG were -0.409 (96% CI: -0.698, -0.120; P = 0.004) and 0.227 (95% CI: 0.039, 0.415; P = 0.026), respectively. The βIVs for TGs and LDL-C were not significant.

CONCLUSIONS

This study has provided evidence for the biologically plausible causal effects of diabetes and adiposity by BMI on different elements of the lipid profile using Mendelian randomization analyses.

Increased Perinatal Morbidity and Mortality Among Asian American and Pacific Islander Women in the United States

BACKGROUND

Asian American/Pacific Islanders (AAPIs) are the fastest-growing racial group in the United States. Despite a higher socioeconomic status, AAPI women experience higher rates of maternal morbidity and mortality.

METHODS

Using the National Inpatient Sample, we performed a retrospective cohort analysis of women who were hospitalized for delivery from 2002 to 2013. The primary outcome variable was inpatient mortality rate, and the presence of severe maternal morbidities was estimated using the Bateman Comorbidity Index, a validated tool for predicting obstetric morbidity.

RESULTS

AAPI women presenting for delivery between 2003 and 2012 were older, more likely to reside in a zip code in the top quartile of annual income, be privately insured than Caucasian women, and less likely to have a higher Bateman Comorbidity Index. However, AAPI women had a higher likelihood of postpartum hemorrhage (3.4% vs 2.7%, P < .001), uterine atony, severe perineal lacerations, and severe maternal morbidities. Procedures such as transfusion, hysterectomy, and mechanical ventilation were also more common in AAPI women. Furthermore, AAPI women had a higher mortality rate that persisted despite adjustment for an apparently higher income and comorbidities (odds ratio 1.72, 95% confidence interval: 1.14-2.59, P = .01).

CONCLUSIONS

Despite having a higher socioeconomic status, AAPI women had higher rates of maternal mortality during hospitalization for delivery. This increase persisted even after adjustment for factors known to affect peripartum outcomes. Further investigation is needed to better clarify the causes of racial differences in maternal morbidity and mortality.

Single-cell transcriptomics of East-Asian pancreatic islets cells

Single-cell RNA-seq (scRNA-seq) of pancreatic islets have reported on α- and β-cell gene expression in mice and subjects of predominantly European ancestry. We aimed to assess these findings in East-Asian islet-cells. 448 islet-cells were captured from three East-Asian non-diabetic subjects for scRNA-seq. Hierarchical clustering using pancreatic cell lineage genes was used to assign cells into cell-types. Differentially expressed transcripts between α- and β-cells were detected using ANOVA and in silico replications of mouse and human islet cell genes were performed. We identified 118 α, 105 β, 6 δ endocrine cells and 47 exocrine cells. Besides INS and GCG, 26 genes showed differential expression between α- and β-cells. 10 genes showed concordant expression as reported in rodents, while FAM46A was significantly discordant. Comparing our East-Asian data with data from primarily European subjects, we replicated several genes implicated in nuclear receptor activations, acute phase response pathway, glutaryl-CoA/tryptophan degradations and EIF2/AMPK/mTOR signaling. Additionally, we identified protein ubiquitination to be associated among East-Asian β-cells. We report on East-Asian α- and β-cell gene signatures and substantiate several genes/pathways. We identify expression signatures in East-Asian β-cells that perhaps reflects increased susceptibility to cell-death and warrants future validations to fully appreciate their role in East-Asian diabetes pathogenesis.

Common variants of HNF1A gene are associated with diabetic retinopathy and poor glycemic control in normal-weight Japanese subjects with type 2 diabetes mellitus

AIM

This study investigated the associations between the common hepatocyte nuclear factor-1A (HNF1A) variants and the risk of diabetic retinopathy (DR) in relation to the glycemic control and weight status.

METHODS

A retrospective longitudinal analysis was conducted among 354 Japanese patients with type 2 diabetes mellitus (T2DM) (mean follow-up duration: 5.8±2.5 years). The multivariable-adjusted hazard ratio (HR) for the cumulative incidence of DR was calculated using a Cox proportional hazard model. During the observation period, the longitudinal associations of the HNF1A diplotypes with the risk of DR and the clinical parameters were also analyzed using the generalized estimating equations approach.

RESULTS

The combination of risk variants, i.e., rs1169288-C, rs1183910-A and rs2464196-A, was defined as the H1 haplotype. The incidence of DR was higher in the H1/H1 diplotype cases than in the others (HR 2.75 vs. non-H1/non-H1; p=0.02). Only in normal-weight subjects, the risks of DR and poor glycemic control were higher in the H1/H1 diplotype cases than in the others [odds ratio 4.08 vs. non-H1/non-H1, p=0.02; odds ratio 3.03, p=0.01; respectively].

CONCLUSIONS

This study demonstrated that the common HNF1A diplotype of three risk variants may be an independent risk factor for the development of DR resulting from poor glycemic control in normal-weight patients with T2DM. These results need to be replicated in larger and more varied study populations.

Genetic variants associated with lean and obese type 2 diabetes in a Han Chinese population: A case-control study

Type 2 diabetes (T2D) is highly phenotypically heterogeneous. Genetics of the heterogeneity of lean and obese T2D is not clear. The aim of the present study was to identify the associations of T2D-related genetic variants with the risks for lean and obese T2D among the Chinese Han population. A case-control study consisting of 5338 T2D patients and 4663 normal glycemic controls of Chinese Han recruited in the Chinese National Diabetes and Metabolic Disorders Study was conducted. T2D cases were identified according to the 1999 World Health Organization criteria. Lean T2D was defined as T2D patient with a body mass index (BMI) <23 kg/m, whereas obese T2D was defined as T2D patient with a BMI ≥28 kg/m. Twenty-five genome-wide association studies previously validated T2D-related single-nucleotide polymorphisms (SNPs) were genotyped. A genotype risk score (GRS) based on the 25 SNPs was created. After adjusting for multiple covariates, SNPs in or near CDKAL1, CDKN2BAS, KCNQ1, TCF7L2, CDC123/CAMK1D, HHEX, and TCF2 were associated with the risk for lean T2D, and SNPs in or near KCNQ1 and FTO were associated with the risk for obese T2D. The results showed that the GRS for 25 T2D-related SNPs was more strongly associated with the risk for lean T2D (Ptrend = 2.66 × 10) than for obese T2D (Ptrend = 2.91 × 10) in our study population. Notably, the T2D GRS contributed to lower obesity-related measurements and greater β-cell dysfunction, including lower insulin levels in oral glucose tolerance test, decreased insulinogenic index, and Homeostasis Model Assessment for β-cell Function. In conclusion, our findings identified T2D-related genetic loci that contribute to the risk of lean and obese T2D individually and additively in a Chinese Han population. Moreover, the study highlights the contribution of known T2D genomic loci to the heterogeneity of lean and obese T2D in Chinese Hans.

Diabetes and Risk of Arterial Stiffness: A Mendelian Randomization Analysis

We aimed to explore the causal association between type 2 diabetes (T2D) and increased arterial stiffness. We performed a Mendelian randomization (MR) analysis in 11,385 participants from a well-defined community study in Shanghai during 2011-2013. We genotyped 34 T2D-associated common variants identified in East Asians and created a genetic risk score (GRS). We assessed arterial stiffness noninvasively with the measurement of brachial-ankle pulse wave velocity (baPWV). We used the instrumental variable (IV) estimator to qualify the causal relationship between T2D and increased arterial stiffness. We found each 1-SD increase in T2D_GRS was associated with 6% higher risk in increased arterial stiffness (95% CI 1.01, 1.12), after adjustment of other metabolic confounders. Using T2D_GRS as the IV, we demonstrated a causal relationship between T2D and arterial stiffening (odds ratio 1.24, 95% CI 1.06, 1.47; P = 0.008). When categorizing the genetic loci according to their effect on insulin secretion or resistance, we found genetically determined decrease in insulin secretion was associated with increase in baPWV (βIV = 122.3 cm/s, 95% CI 41.9, 204.6; P = 0.0005). In conclusion, our results provide evidence supporting a causal association between T2D and increased arterial stiffness in a Chinese population.

Type 2 Diabetes, Diabetes Genetic Score and Risk of Decreased Renal Function and Albuminuria: A Mendelian Randomization Study

BACKGROUND

Type 2 diabetes (T2D) is a risk factor for dysregulation of glomerular filtration rate (GFR) and albuminuria. However, whether the association is causal remains unestablished.

RESEARCH DESIGN AND METHODS

We performed a Mendelian Randomization (MR) analysis in 11,502 participants aged 40 and above, from a well-defined community in Shanghai during 2011-2013, to explore the causal association between T2D and decreased estimated GFR (eGFR) and increased urinary albumin-to-creatinine ratio (uACR). We genotyped 34 established T2D common variants in East Asians, and created a T2D-genetic risk score (GRS). We defined decreased eGFR as eGFR<90ml/min/1.73m(2) and increased uACR as uACR≥30mg/g. We used the T2D_GRS as the instrumental variable (IV) to quantify the causal effect of T2D on decreased eGFR and increased uACR.

RESULTS

Each 1-standard deviation (SD, 3.90 points) increment in T2D_GRS was associated with decreased eGFR: odds ratio (OR)=1.18 (95% confidence interval [CI]: 1.01, 1.30). In the MR analysis, we demonstrated a causal relationship between genetically determined T2D and decreased eGFR (OR=1.47, 95% CI: 1.15, 1.88, P=0.0003). When grouping the genetic loci according to their relations with either insulin secretion (IS) or insulin resistance (IR), we found both IS_GRS and IR_GRS were significantly related to decreased eGFR (both P<0.02). In addition, T2D_GRS and IS_GRS were significantly associated with Log-uACR (both P=0.04).

CONCLUSION

Our results provide novel evidence for a causal association between T2D and decreased eGFR by using MR approach in a Chinese population.

Alcohol Consumption and the Risk of Type 2 Diabetes: A Systematic Review and Dose-Response Meta-analysis of More Than 1.9 Million Individuals From 38 Observational Studies

OBJECTIVE

Observational studies indicate that moderate levels of alcohol consumption may reduce the risk of type 2 diabetes. In addition to providing an updated summary of the existing literature, this meta-analysis explored whether reductions in risk may be the product of misclassification bias.

RESEARCH DESIGN AND METHODS

A systematic search was undertaken, identifying studies that reported a temporal association between alcohol consumption and the risk of type 2 diabetes. No restrictions were placed upon the language or date of publication. Non-English publications were, where necessary, translated using online translation tools. Models were constructed using fractional polynomial regression to determine the best-fitting dose-response relationship between alcohol intake and type 2 diabetes, with a priori testing of sex and referent group interactions.

RESULTS

Thirty-eight studies met the selection criteria, representing 1,902,605 participants and 125,926 cases of type 2 diabetes. A conventional noncurrent drinking category was reported by 33 studies, while five reported a never-drinking category. Relative to combined abstainers, reductions in the risk of type 2 diabetes were present at all levels of alcohol intake <63 g/day, with risks increasing above this threshold. Peak risk reduction was present between 10-14 g/day at an 18% decrease in hazards. Stratification of available data revealed that reductions in risk may be specific to women only and absent in studies that adopted a never-drinking abstention category or sampled an Asian population region.

CONCLUSIONS

Reductions in risk among moderate alcohol drinkers may be confined to women and non-Asian populations. Although based on a minority of studies, there is also the possibility that reductions in risk may have been overestimated by studies using a referent group contaminated by less healthy former drinkers.

CNV Analysis Associates AKNAD1 with Type-2 Diabetes in Jordan Subpopulations

Previous studies have identified a number of single nucleotide polymorphisms (SNPs) associated with type-2 diabetes (T2D), but copy number variation (CNV) association has rarely been addressed, especially in populations from Jordan. To investigate CNV associations for T2D in populations in Jordan, we conducted a CNV analysis based on intensity data from genome-wide SNP array, including 34 T2D cases and 110 healthy controls of Chechen ethnicity, as well as 34 T2D cases and 106 healthy controls of Circassian ethnicity. We found a CNV region in protein tyrosine phosphatase receptor type D (PTPRD) with significant association with T2D. PTPRD has been reported to be associated with T2D in genome-wide association studies (GWAS). We additionally identified 16 CNV regions associated with T2D which overlapped with gene exons. Of particular interest, a CNV region in the gene AKNA Domain Containing 1 (AKNAD1) surpassed the experiment-wide significance threshold. Endoplasmic reticulum (ER)-related pathways were significantly enriched among genes which are predicted to be functionally associated with human or mouse homologues of AKNAD1. This is the first CNV analysis of a complex disease in populations of Jordan. We identified and experimentally validated a significant CNVR in gene AKNAD1 associated with T2D.

β cell dysfunction versus insulin resistance in the pathogenesis of type 2 diabetes in East Asians

Type 2 diabetes (T2DM) is one of the most serious global health problems and is mainly a result of the drastic increase in East Asia, which includes over a fourth of the global diabetes population. Lifestyle factors and ethnicity are two determinants in the etiology of T2DM, and lifestyle changes such as higher fat intake and less physical activity link readily to T2DM in East Asians. It is widely recognized that T2DM in East Asians is characterized primarily by β cell dysfunction, which is evident immediately after ingestion of glucose or meal, and less adiposity compared to the disease in Caucasians. These pathophysiological differences have an important impact on therapeutic approaches. Here, we revisit the pathogenesis of T2DM in light of β cell dysfunction versus insulin resistance in East Asians and discuss ethnic differences in the contributions of insulin secretion and insulin resistance, together with incretin secretin and action, to glucose intolerance.

Habitual coffee intake, genetic polymorphisms, and type 2 diabetes

BACKGROUND

The association between coffee intake and type 2 diabetes may be modulated by common genetic variation.

OBJECTIVE

The purpose of this study was to examine the association between habitual coffee intake and the risk of type 2 diabetes and to determine whether this association varied by genetic polymorphisms related to type 2 diabetes in Korean adults.

DESIGN AND METHODS

A population-based cohort study over a follow-up of 4 years was conducted. A total of 4077 Korean men and women aged 40-69 years with a normal glucose level at baseline were included. Coffee intake was assessed using a validated food frequency questionnaire, and incident type 2 diabetes or prediabetes was defined by oral glucose tolerance test or fasting blood glucose test. The genomic DNA samples were genotyped with the Affymetrix Genome-Wide Human SNP Array 5.0, and nine single-nucleotide polymorphisms related to type 2 diabetes in East Asian populations were extracted.

RESULTS

A total of 120 cases of type 2 diabetes and 1128 cases of prediabetes were identified. After adjustment for potential confounding factors, we observed an inverse association, but without any clear linear trend, between coffee intake and the combined risk of type 2 diabetes and prediabetes. We found that inverse associations between habitual coffee intake and the combined risk of type 2 diabetes and prediabetes were limited to those with the T-allele (GT/TT) of rs4402960 in IGF2BP2, those with the G-allele (GG/GC) of rs7754840 in CDKAL1, or those with CC of rs5215 in KCNJ11.

CONCLUSION

We found a lower risk of prediabetes and type 2 diabetes combined with coffee intake among individuals with the GT/TT of IGF2BP2 rs4402960, GG/GC of CDKAL1 rs7754840, or CC of KCNJ11 rs5215, which are known to be related to type 2 diabetes in East Asians.

Efficacy of dipeptidyl-peptidase-4 inhibitors and impact on β-cell function in Asian and Caucasian type 2 diabetes mellitus patients: A meta-analysis

BACKGROUND

This work aimed to compare the efficacy of dipeptidyl peptidase-IV (DPP-4) inhibitors and their impact on β-cell function in Asian and Caucasian patients with type 2 diabetes mellitus.

METHODS

Databases were systematically searched and qualifying studies that compared DPP-4 inhibitors with other antidiabetic medications in type 2 diabetes were included.

RESULTS

A total of 68 studies were included in the meta-analysis. Comparison of DPP-4 inhibitors with placebo in Asian patients showed a decrease in glycosylated hemoglobin (HbA1c ) favoring DPP-4 inhibitors (weighted mean difference [WMD], -0.81%; 95% confidence interval [CI], -0.95% to -0.68%; P < 0.001). Comparison of HbA1c changes between Asian and Caucasian patients showed a significant between-group difference of -0.18% (95% CI, -0.32% to -0.04%; P = 0.011) when compared with placebo. In Asian patients, the homeostatic model assessment for β-cell function (HOMA-β) was increased with DPP-4 inhibitors compared with placebo (WMD, 7.90; 95% CI, 4.29 to 11.51; P < 0.001), although to a lesser extent in Caucasian patients. Comparisons between Asian and Caucasian patients showed a significant between-group difference of -4.97 (95% CI, -9.86 to -0.09; P = 0.046) compared with placebo. Body weight increase with DPP-4 inhibitors compared with placebo was comparable in Asian and Caucasian studies (WMD, 0.37 kg and 0.45 kg and 95% CI, 0.04-0.69 and 0.27-0.62, respectively).

CONCLUSIONS

The glucose-lowering efficacy of DPP-4 inhibitors was greater in Asian patients than in Caucasian patients, although the effect on β-cell function was inferior in Asian patients. The effect of DPP-4 inhibitors on insulin resistance and body weight in Asian patients was comparable with that observed in Caucasian patients.

Multicenter cohort study of diabetes mellitus and impaired fasting glucose in HIV-infected patients in China

BACKGROUND

As life expectancy increases, HIV-infected patients are facing a wide array of metabolic complications, including diabetes mellitus (DM) and impaired fasting glucose (IFG). However, little is known about the incidence of and risk factors for glycemic disorders in Chinese HIV-infected patients.

METHODS

Longitudinal data were pooled from a multicenter clinical trial of combination antiretroviral regimens between 2009 and 2010 across Mainland China. DM was defined as fasting glucose level ≥7.0 mmol/L and IFG as between 5.6 and 6.9 mmol/L on 2 separate measurements. We calculated the incidence densities of DM and IFG. Risk factors for DM and IFG were also identified.

RESULTS

Four hundred fifteen patients contributed 457.35 person-years of follow-up. The incidence densities of DM and IFG were 2.62 and 35.64 per 100 person-years, respectively. In a multivariate analysis, advanced age [adjusted hazard ratio (HR): 1.03, 95% confidence interval (CI): 1.01 to 1.04], hepatitis B virus coinfection (adjusted HR: 1.59, 95% CI: 1.06 to 2.38), and baseline fasting glucose (adjusted HR: 1.28, 95% CI: 1.00 to 1.63) were associated with DM and IFG.

CONCLUSIONS

A high incidence of DM and IFG was detected in Chinese HIV-infected patients receiving combination antiretroviral therapy. Clinicians should be aware of the potential for an increased risk of glycemic disorders in Chinese HIV-infected patients, particularly those of advanced age, with hepatitis B virus coinfection or high baseline fasting glucose.

Association of type 2 diabetes genetic variants with breast cancer survival among Chinese women

Objective

To evaluate whether the genetic susceptibility of T2D was associated with overall survival (OS) and disease-free survival (DFS) outcomes for breast cancer (BC).

Methods

Included in the study were 6346 BC patients who participated in three population-based epidemiological studies of BC and were genotyped with either GWAS or Exome-chip. We constructed a genetic risk score (GRS) for diabetes using risk variants identified from the GWAS catalog (http://genome.gov/gwastudies) that were associated with T2D risk at a minimum significance level of P ≤ 5.0E-8 among Asian population and evaluated its associations with BC outcomes with Cox proportional hazards models.

Results

During a median follow-up of 8.08 years (range, 0.01–16.95 years), 1208 deaths were documented in 6346 BC patients. Overall, the diabetes GRS was not associated with OS and DFS. Analyses stratified by estrogen receptor status (ER) showed that the diabetes GRS was inversely associated with OS among women with ER- but not in women with ER+ breast cancer; the multivariable adjusted HR was 1.38 (95% CI: 1.05–1.82) when comparing the highest to the lowest GRS quartiles. The association of diabetes GRS with OS varied by diabetes status (P for interaction <0.01). In women with history of diabetes, higher diabetes GRS was significantly associated with worse OS, with HR of 2.22 (95% CI: 1.28–3.88) for the highest vs. lowest quartile, particularly among women with an ER- breast cancer, with corresponding HR being 4.59 (95% CI: 1.04–20.28). No significant association between the diabetes GRS and OS was observed across different BMI and PR groups.

Conclusions

Our study suggested that genetic susceptibility of T2D was positively associated with total mortality among women with ER- breast cancer, particularly among subjects with a history of diabetes. Additional studies are warranted to verify the associations and elucidate the underlying biological mechanism.

Obesity-related genomic loci are associated with type 2 diabetes in a Han Chinese population

BACKGROUND AND AIMS

Obesity is a well-known risk factor for type 2 diabetes. Genome-wide association studies have identified a number of genetic loci associated with obesity. The aim of this study is to examine the contribution of obesity-related genomic loci to type 2 diabetes in a Chinese population.

METHODS

We successfully genotyped 18 obesity-related single nucleotide polymorphisms among 5338 type 2 diabetic patients and 4663 controls. Both individual and joint effects of these single nucleotide polymorphisms on type 2 diabetes and quantitative glycemic traits (assessing β-cell function and insulin resistance) were analyzed using logistic and linear regression models, respectively.

RESULTS

Two single nucleotide polymorphisms near MC4R and GNPDA2 genes were significantly associated with type 2 diabetes before adjusting for body mass index and waist circumference (OR (95% CI) = 1.14 (1.06, 1.22) for the A allele of rs12970134, P = 4.75×10(-4); OR (95% CI) = 1.10 (1.03, 1.17) for the G allele of rs10938397, P = 4.54×10(-3)). When body mass index and waist circumference were further adjusted, the association of MC4R with type 2 diabetes remained significant (P = 1.81×10(-2)) and that of GNPDA2 was attenuated (P = 1.26×10(-1)), suggesting the effect of the locus including GNPDA2 on type 2 diabetes may be mediated through obesity. Single nucleotide polymorphism rs2260000 within BAT2 was significantly associated with type 2 diabetes after adjusting for body mass index and waist circumference (P = 1.04×10(-2)). In addition, four single nucleotide polymorphisms (near or within SEC16B, BDNF, MAF and PRL genes) showed significant associations with quantitative glycemic traits in controls even after adjusting for body mass index and waist circumference (all P values<0.05).

CONCLUSIONS

This study indicates that obesity-related genomic loci were associated with type 2 diabetes and glycemic traits in the Han Chinese population.

Assessment of metabolic status in young Japanese females using postprandial glucose and insulin levels

Lifestyle-related diseases develop through the accumulation of undesirable lifestyle habits both prior to the onset of disease as well as during normal healthy life. Accordingly, early detection of, and intervention in, metabolic disorders is desirable, but is hampered by the lack of an established evaluation index for young individuals. The purpose of this study was to investigate the utility of a biomarker of health in young female subjects. The subjects were young healthy Japanese females in whom energy expenditure was measured for a period of 210 min after a test meal. In addition, Δplasma glucose and Δserum insulin were calculated from the fasting and 30 min values. ΔPlasma glucose and Δserum insulin levels varied widely compared to fasting levels. Both the area under the curve of carbohydrate oxidation rate and serum free fatty acid levels were higher in individuals in the high Δplasma glucose group. Moreover, Δplasma glucose was higher in individuals in the high Δserum insulin group than in the low Δserum insulin group. We conclude that nutritional balanced liquid loading test using Δplasma glucose and Δserum insulin as the evaluation index is useful for the detection of primary metabolic disorders in young females.

A common functional regulatory variant at a type 2 diabetes locus upregulates ARAP1 expression in the pancreatic beta cell

Genome-wide association studies (GWASs) have identified more than 70 loci associated with type 2 diabetes (T2D), but for most, the underlying causal variants, associated genes, and functional mechanisms remain unknown. At a T2D- and fasting-proinsulin-associated locus on 11q13.4, we have identified a functional regulatory DNA variant, a candidate target gene, and a plausible underlying molecular mechanism. Fine mapping, conditional analyses, and exome array genotyping in 8,635 individuals from the Metabolic Syndrome in Men study confirmed a single major association signal between fasting proinsulin and noncoding variants (p = 7.4 × 10(-50)). Measurement of allele-specific mRNA levels in human pancreatic islet samples heterozygous for rs11603334 showed that the T2D-risk and proinsulin-decreasing allele (C) is associated with increased ARAP1 expression (p < 0.02). We evaluated four candidate functional SNPs for allelic effects on transcriptional activity by performing reporter assays in rodent pancreatic beta cell lines. The C allele of rs11603334, located near one of the ARAP1 promoters, exhibited 2-fold higher transcriptional activity than did the T allele (p < 0.0001); three other candidate SNPs showed no allelic differences. Electrophoretic mobility shift assays demonstrated decreased binding of pancreatic beta cell transcriptional regulators PAX6 and PAX4 to the rs11603334 C allele. Collectively, these data suggest that the T2D-risk allele of rs11603334 could abrogate binding of a complex containing PAX6 and PAX4 and thus lead to increased promoter activity and ARAP1 expression in human pancreatic islets. This work suggests that increased ARAP1 expression might contribute to T2D susceptibility at this GWAS locus.

A replication study of 19 GWAS-validated type 2 diabetes at-risk variants in the Lebanese population

AIM

Recent genome-wide association scans (GWAS) and replication studies have expanded the list of validated type 2 diabetes (T2DM) susceptibility loci. We replicated T2DM association of 19 SNPs from 15 candidate loci in Lebanese Arabs.

METHODS

Case-control association study, comprising 995 T2DM patients and 1076 control participants. We genotyped by the allelic discrimination method 19 SNPs in/near ADAM30, NOTCH2, THADA, TMEFF2, COL8A1, ADAMTS9-AS2, WFS1, JAZF1, SLC30A8, KCNQ1, LOC387761, ALX4, TSPAN8, FTO, and HNF1.

RESULTS

Allele frequencies of the tested SNPs were comparable with those of Caucasians. COL8A1 rs792837 (P=2.9 × 10(-9)), KCNQ1 rs2237892 (P=1.8 × 10(-18)) and rs2237895 (P=0.002), ALX4 rs729287 (Pc=7.5 × 10(-5)), and HNF1 rs4430796 (P=0.003) were significantly associated with T2DM, with similar effect sizes to those of Europeans. While FTO rs8050136 and rs17817449, ADAMTS9 rs4607103, and WFS1 rs10010131 were initially associated with T2DM, this was lost upon multiple testing correction. The remaining variants were not associated with T2DM, possibly resulting from insufficient power to detect smaller allele effects.

CONCLUSION

In addition to previous findings on the association of IGF2BP2, CDKAL1, TCF7L2 variants with T2DM among Lebanese, here we extend these by validating the association of five additional loci with T2DM in Lebanese Arabs.

Diabetes and its comorbidities--where East meets West

Fetal programming associated with in utero exposure to maternal stress is thought to alter gene expression, resulting in phenotypes that promote survival in a pathogen-rich and nutrient-poor environment but substantially increase the risk of cardiovascular, metabolic and renal disorders (such as diabetes mellitus) in adults with obesity. These (epi)genetic phenomena are modified by environmental and socioeconomic factors, resulting in multiple subphenotypes and clinical consequences. In individuals from areas undergoing rapid economic development, which is associated with a transition from communicable to noncommunicable diseases, an efficient innate immune response can exaggerate obesity-associated inflammation. By contrast, in individuals with a genetic predisposition to autoimmune or monogenic diabetes mellitus, obesity can lead to atypical presentation of diabetes mellitus, termed 'double diabetes mellitus'. The increasingly young age at diagnosis of diabetes mellitus in developing countries results in prolonged exposure to glucolipotoxicity, low-grade inflammation and increased oxidative stress, which put enormous strain on pancreatic β cells and renal function. These conditions create a metabolic milieu conducive to cancer growth. This Review discusses how rapid changes in technology and human behaviour have brought on the global epidemic of metabolic diseases, and suggests that solutions will be based on using system change, technology and behavioural strategies to combat this societal-turned-medical problem.

A genome-wide search for type 2 diabetes susceptibility genes in an extended Arab family

Twenty percent of people aged 20 to 79 have type 2 diabetes (T2D) in the United Arab Emirates (UAE). Genome-wide association studies (GWAS) to identify genes for T2D have not been reported for Arab countries. We performed a discovery GWAS in an extended UAE family (N=178; 66 diabetic; 112 healthy) genotyped on the Illumina Human 660 Quad Beadchip, with independent replication of top hits in 116 cases and 199 controls. Power to achieve genome-wide significance (commonly P=5×10(-8)) was therefore limited. Nevertheless, transmission disequilibrium testing in FBAT identified top hits at Chromosome 4p12-p13 (KCTD8: rs4407541, P=9.70×10(-6); GABRB1: rs10517178/rs1372491, P=4.19×10(-6)) and 14q13 (PRKD1: rs10144903, 3.92×10(-6)), supported by analysis using a linear mixed model approximation in GenABEL (4p12-p13 GABRG1/GABRA2: rs7662743, Padj-agesex=2.06×10(-5); KCTD8: rs4407541, Padj-agesex=1.42×10(-4); GABRB1: rs10517178/rs1372491, Padj-agesex=0.027; 14q13 PRKD1: rs10144903, Padj-agesex=6.95×10(-5)). SNPs across GABRG1/GABRA2 did not replicate, whereas more proximal SNPs rs7679715 (Padj-agesex=0.030) and rs2055942 (Padj-agesex=0.022) at COX7B2/GABRA4 did, in addition to a trend distally at KCTD8 (rs4695718: Padj-agesex=0.096). Modelling of discovery and replication data support independent signals at GABRA4 (rs2055942: Padj-agesex-combined=3×10(-4)) and at KCTD8 (rs4695718: Padj-agesex-combined=2×10(-4)). Replication was observed for PRKD1 rs1953722 (proxy for rs10144903; Padj-agesex=0.031; Padj-agesex-combined=2×10(-4)). These genes may provide important functional leads in understanding disease pathogenesis in this population.

Genetics of type 2 diabetes and potential clinical implications

Type 2 diabetes (T2DM) is a common complex metabolic disorder that has a strong genetic component. Recent advances in genome-wide association studies have revolutionized our knowledge regarding the genetics of T2DM. There are at least 64 common genetic variants that are strongly associated with T2DM. However, the pathophysiologic roles of these variants are mostly unknown and require further functional characterization. The variants identified so far have a small effect size and their added effect explains less than 10 % of the T2DM heritability. The current ongoing whole exome and whole genome studies of T2DM are focused on identifying functionally important rare variants that have a stronger effect. Through these efforts, we will have a better understanding of the genetic architecture of T2DM and its pathophysiology. The potential clinical applications of genetic studies of T2DM include risk prediction, identification of novel therapeutic targets, genetic prediction of efficacy and toxicity of anti-diabetic medications, and eventually optimization of patient care through personalized genomic medicine. We hope further research in genetics of T2DM could aid patient care and improve outcomes of T2DM patients.