Association of Protein Tyrosine Phosphatase Receptor Type D and Serine Racemase Genetic Variants with Type 2 Diabetes in Malaysian Indians.

Introduction: Type 2 diabetes (T2D) candidate genes, protein tyrosine phosphatase receptor type D (PTPRD), and serine racemase (SRR) were suggested by a genome-wide association study (GWAS) in the Chinese population. Association studies have been replicated among East Asian populations. The association of PTPRD and SRR genetic variants with T2D in Southeast Asian populations still needs to be studied. This study aimed to investigate the association of PTPRD and SSR genetic variants with T2D in Malaysian Indian subjects. Methods: The single nucleotide polymorphisms (SNPs) of PTPRD (rs649891 and rs17584499) and SRR (rs4523957, rs391300, and rs8081273) were genotyped in 397 T2D and 285 normal Malaysian Indian subjects. Results: The homozygous dominant genotype of rs17584499 is frequent in diabetic patients (56.5%) compared to normal subjects (47.3%). In contrast, the homozygous recessive genotype of rs8081273 is more frequent among normal subjects (12.5%) than diabetic patients (5.6%). The dominant genetic model showed that PTPRD rs17584499 (CC) is a risk factor for T2D (OR = 1.42, P = 0.029), whereas the recessive genetic model showed that SRS SNP rs8081273 was protective for T2D (OR = 0.42, P = 0.003). Conclusion: This study confirmed the association of PTPRD rs17584499 genetic variations with T2D in Malaysian Indians. While the SRR rs8081273 (TT) genotype showed protection against T2D, more investigation in different populations is required to confirm this protection.

Altered circulating concentrations of active glucagon-like peptide (GLP-1) and dipeptidyl peptidase 4 (DPP4) in obese subjects and their association with insulin resistance.

OBJECTIVES: Soluble DPP4 (sDPP4) is a novel adipokine that degrades glucagon-like peptide (GLP-1). We evaluated the fasting serum levels of active GLP-1 and sDPP4 in obese, overweight and normal weight subjects to assess the association between sDPP4 levels, active GLP-1 levels and insulin resistance in obese subjects. METHODS: The study involved 235 Malaysian subjects who were randomly selected (66 normal weight subjects, 97 overweight, 59 obese subjects, and 13 subjects who were underweight). Serum sDPP4 and active GLP-1 levels were examined by enzyme-linked immunosorbent assay (ELISA). Also, body mass index kg/m2 (BMI), lipid profiles, insulin and glucose levels were evaluated. Insulin resistance (IR) was estimated via the homeostasis model assessment for insulin resistance (HOMA-IR). RESULTS: Serum sDPP4 levels were significantly higher in obese subjects compared to normal weight subjects (p=0.034), whereas serum levels of active GLP-1 were lower (p=0.021). In obese subjects, sDPP4 levels correlated negatively with active GLP-1 levels (r2=-0.326, p=0.015). Furthermore, linear regression showed that sDPP4 levels were positively associated with insulin resistance (B=82.28, p=0.023) in obese subjects. CONCLUSION: Elevated serum sDPP4 levels and reduced GLP-1 levels were observed in obese subjects. In addition, sDPP4 levels correlated negatively with active GLP-1 levels but was positively associated with insulin resistance. This finding provides evidence that sDPP4 and GLP-1 may play an important role in the pathogenesis of obesity, suggesting that sDPP4 may be valuable as an early marker for the augmented risk of obesity and insulin resistance.

Association of DPP4 Gene Polymorphisms with Type 2 Diabetes Mellitus in Malaysian Subjects.

BACKGROUND: Genetic polymorphisms of the Dipeptidyl Peptidase 4 (DPP4) gene may play a role in the etiology of type 2 diabetes mellitus (T2DM). This study aimed to investigate the possible association of single nucleotide polymorphisms (SNPs) of the DPP4 gene in Malaysian subjects with T2DM and evaluated whether they had an effect on the serum levels of soluble dipeptidyl peptidase 4 (sDPP-IV). METHOD: Ten DPP4 SNPs were genotyped by TaqMan genotyping assays in 314 subjects with T2DM and 235 controls. Of these, 71 metabolic syndrome (MetS) subjects were excluded from subsequent analysis. The odds ratios (ORs) and their 95% confidence interval (CIs) were calculated using multiple logistic regression for the association between the SNPs of DPP4 and T2DM. In addition, the serum levels of sDPP-IV were investigated to evaluate the association of the SNPs of DPP4 with the sDPP-IV levels. RESULTS: Dominant, recessive, and additive genetic models were employed to test the association of DPP4 polymorphisms with T2DM, after adjusting for age, race, gender and BMI. The rs12617656 was associated with T2DM in Malaysian subjects in the recessive genetic model (OR = 1.98, p = 0.006), dominant model (OR = 1.95, p = 0.008), and additive model (OR = 1.63, p = 0.001). This association was more pronounced among Malaysian Indians, recessive (OR = 3.21, p = 0.019), dominant OR = 3.72, p = 0.003) and additive model (OR = 2.29, p = 0.0009). The additive genetic model showed that DPP4 rs4664443 and rs7633162 polymorphisms were associated with T2DM (OR = 1.53, p = 0.039), and (OR = 1.42, p = 0.020), respectively. In addition, the rs4664443 G>A polymorphism was associated with increased sDPP-IV levels (p = 0.042) in T2DM subjects. CONCLUSIONS: DPP4 polymorphisms were associated with T2DM in Malaysian subjects, and linked to variations in sDPP-IV levels. In addition, these associations were more pronounced among Malaysian Indian subjects.

Serum Levels of Soluble CD26/Dipeptidyl Peptidase-IV in Type 2 Diabetes Mellitus and Its Association with Metabolic Syndrome and Therapy with Antidiabetic Agents in Malaysian Subjects.

BACKGROUND: A soluble form of CD26/dipeptidyl peptidase-IV (sCD26/DPP-IV) induces DPP-IV enzymatic activity that degrades incretin. We investigated fasting serum levels of sCD26/DPP-IV and active glucagon-like peptide-1 (GLP-1) in Malaysian patients with type 2 diabetes mellitus (T2DM) with and without metabolic syndrome (MetS), as well as the associations between sCD26/DPP-IV levels, MetS, and antidiabetic therapy. METHODS: We assessed sCD26/DPP-IV levels, active GLP-1 levels, body mass index (BMI), glucose, insulin, A1c, glucose homeostasis indices, and lipid profiles in 549 Malaysian subjects (including 257 T2DM patients with MetS, 57 T2DM patients without MetS, 71 non-diabetics with MetS, and 164 control subjects without diabetes or metabolic syndrome). RESULTS: Fasting serum levels of sCD26/DPP-IV were significantly higher in T2DM patients with and without MetS than in normal subjects. Likewise, sCD26/DPP-IV levels were significantly higher in patients with T2DM and MetS than in non-diabetic patients with MetS. However, active GLP-1 levels were significantly lower in T2DM patients both with and without MetS than in normal subjects. In T2DM subjects, sCD26/DPP-IV levels were associated with significantly higher A1c levels, but were significantly lower in patients using monotherapy with metformin. In addition, no significant differences in sCD26/DPP-IV levels were found between diabetic subjects with and without MetS. Furthermore, sCD26/DPP-IV levels were negatively correlated with active GLP-1 levels in T2DM patients both with and without MetS. In normal subjects, sCD26/DPP-IV levels were associated with increased BMI, cholesterol, and LDL-cholesterol (LDL-c) levels. CONCLUSION: Serum sCD26/DPP-IV levels increased in T2DM subjects with and without MetS. Active GLP-1 levels decreased in T2DM patients both with and without MetS. In addition, sCD26/DPP-IV levels were associated with Alc levels and negatively correlated with active GLP-1 levels. Moreover, metformin monotherapy was associated with reduced sCD26/DPP-IV levels. In normal subjects, sCD26/DPP-IV levels were associated with increased BMI, cholesterol, and LDL-c.

Association of adipokines, leptin/adiponectin ratio and C-reactive protein with obesity and type 2 diabetes mellitus.

OBJECTIVE: Alterations in plasma adipokines and/or inflammatory parameters in Type 2 DM remain vague as to whether they are due to obesity and/or directly associated with the diabetic state. Our objective was to compare plasma adiponectin, leptin, leptin/adiponectin ratio (LAR) and hs-CRP in obese non-diabetic subjects and non-obese Type 2 DM patients, as well as determining the association of these adipokines with MetS and diabetes-related quantitative traits. METHODS: In this study, 92 Yemeni male volunteers aged 25-60 years old were enrolled, 31 of whom were healthy subjects with BMI < 25 kg/m(2) served as control; 30 non-diabetic obese subjects BMI ≥ 30 kg/m(2) and FBG < 6.1 mmol/l; and 31 non-obese Type 2 DM with FBG > 7 mmol/l and BMI < 25 kg/m(2). RESULTS: Adiponectin was lower in obese subjects, with no differences between non-obese Type 2 DM patients and controls. In contrast, leptin, LAR and hs-CRP were higher in both obese subjects and non-obese Type 2 DM patients. Linear regression analysis showed adiponectin to be associated negatively with BMI, waist circumference, insulin, HOMA-ß and HOMA-IR; whereas leptin, LAR and hs-CRP were associated positively with BMI, waist circumference, TG, FBG, insulin, HOMA-ß and HOMA-IR. Moreover, adiponectin negatively correlated with leptin, LAR and hs-CRP; whereas leptin and LAR positively correlated with hs-CRP and with each other. CONCLUSION: Plasma adiponectin is not affected by diabetes per se, suggesting that its alterations in Type 2 DM may be due to obesity and may be an important link between adiposity, IR and Type 2 DM.

Comparison of adults with insulin resistance (IR) in latent autoimmune diabetes versus IR in glutamic acid decarboxylase antibody-negative diabetes.

INTRODUCTION: Insulin resistance in latent autoimmune diabetes in adults (LADA) patients is controversial. The aim of this study was to evaluate insulin resistance and its related factors (metabolic syndrome parameters) among subjects with LADA and glutamic acid decarboxylase antibodies (GADA) negative diabetes, as well as the impact of these factors on insulin resistance. MATERIALS AND METHODS: GADA levels were investigated in 1140 diabetic patients aged between 30 and 70 years. Insulin resistance and metabolic syndrome parameters were assessed in LADA and GAD-negative diabetic patients by general linear model. In addition, the impact of metabolic syndrome factors on insulin resistance was assessed in LADA and glutamic acid decarboxylase (GAD)-negative diabetic patients. RESULTS: LADA was diagnosed in 33 subjects from 1140 Malaysian diabetic patients (prevalence = 2.9%). The results showed that LADA patients had higher insulin resistance and high density lipoprotein cholesterol (HDLc) (P = 0.003 and 0.00017 respectively) and lower body mass index (BMI) (P = 0.007) compared to GAD-negative diabetic patients. The HDLc was associated with decreased insulin resistance in LADA patients (P = 0.041), whereas HbA1c, triacylglycerides (TG) and waist were associated with increased insulin resistance in GAD-negative diabetic patients (P = 3.6×10⁻¹², 1.01×10⁻5 and 0.004 respectively). HbA1c was highly associated with decreasing ß-cell function in both LADA (P = 0.009) and GAD-negative diabetic subjects (P = 2.2×10⁻²8). CONCLUSION: Insulin resistance is significantly higher in LADA than GAD-negative diabetic Malaysian subjects.

Contribution of SLC30A8 variants to the risk of type 2 diabetes in a multi-ethnic population: a case control study.

BACKGROUND: Several studies have shown the association of solute carrier family 30 (zinc transporter) member 8 (SLC30A8) rs13266634 with type 2 diabetes (T2D). However, the association of alternative variants and haplotypes of SLC30A8 with T2D have not been studied in different populations. The aim of this study is to assess the association of the alternative SLC30A8 variants, rs7002176 and rs1995222 as well as the most common variant, rs13266634 and haplotypes with glutamic acid decarboxylase antibodies (GADA) negative diabetes in Malaysian subjects. METHODS: Single nucleotide polymorphisms (SNPs) of SLC30A8; rs7002176, rs1995222 and rs13266634 were genotyped in 1140 T2D and 973 non-diabetic control subjects. Of these, 33 GADA positive diabetic subjects and 353 metabolic syndrome (MetS) subjects were excluded from subsequent analysis. RESULTS: The recessive genetic model controlled for age, race, gender and BMI shows that the alternative SLC30A8 variant, rs1995222 is associated with GADA negative diabetes (OR = 1.29, P = 0.02) in Malaysian subjects. The most common variant, rs13266634 is also associated with GADA negative diabetes (OR = 1.45, P = 0.001). This association is more pronounced among Malaysian Indians (OR = 1.93, P = 0.001). Moreover, the CG haplotype and CG-CG diplotype have been equally associated with increased diabetic risk (OR = 1.67, P = 8.6 × 10-5). CONCLUSIONS: SLC30A8 SNPs and haplotypes are associated with GADA negative diabetes in Malaysian subjects, and this association is markedly higher among Malaysian Indian subjects.

IGF2BP2 alternative variants associated with glutamic acid decarboxylase antibodies negative diabetes in Malaysian subjects.

BACKGROUND: The association of Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) common variants (rs4402960 and rs1470579) with type 2 diabetes (T2D) has been performed in different populations. The aim of this study was to evaluate the association of alternative variants of IGF2BP2; rs6777038, rs16860234 and rs7651090 with glutamic acid decarboxylase antibodies (GADA) negative diabetes in Malaysian Subjects. METHODS/PRINCIPAL FINDINGS: IGF2BP2; rs6777038, rs16860234 and rs7651090 single nucleotide polymorphisms (SNPs) were genotyped in 1107 GADA negative diabetic patients and 620 control subjects of Asian from Malaysia. The additive genetic model adjusted for age, race, gender and BMI showed that alternative variants; rs6777038, rs16860234 and rs7651090 of IGF2BP2 associated with GADA negative diabetes (OR = 1.21; 1.36; 1.35, P = 0.03; 0.0004; 0.0002, respectively). In addition, the CCG haplotype and diplotype CCG-TCG increased the risk of diabetes (OR = 1.51, P = 0.01; OR = 2.36, P = 0.009, respectively). CONCLUSIONS/SIGNIFICANCE: IGF2BP2 alternative variants were associated with GADA negative diabetes. The IGF2BP2 haplotypes and diplotypes increased the risk of diabetes in Malaysian subject.

Effect of plasminogen activator inhibitor-1 and tissue plasminogen activator polymorphisms on susceptibility to type 2 diabetes in Malaysian subjects.

Elevated activity of plasminogen activator inhibitor-1 (PAI-1) and decreased tissue plasminogen activator (tPA) activity are considered to be important risk factors for type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS). The aim of this study was to investigate the association of the PAI-1 4G/5G and tPA Alu-repeat I/D polymorphisms with T2DM in Malaysian subjects. Serum insulin, coronary risk panel, plasma glucose, and PAI-1 4G/5G and tPA Alu-repeat I/D polymorphisms were studied in 303 T2DM subjects (227 with MetS and 76 without MetS) and 131 normal subjects without diabetes and MetS. Statistical analysis showed that the dominant and additive models of PAI-1 4G/5G polymorphism showed a weak association with T2DM without MetS (OR = 2.35, P = 0.045; OR = 1.67, P = 0.058). On the other hand, the recessive model of the tPA Alu-repeat I/D polymorphism showed an association with T2DM with MetS (OR = 3.32, P = 0.013) whereas the dominant and additive models of the tPA Alu-repeat I/D polymorphism were not associated with T2DM either with or without MetS.

Plasminogen activator inhibitor-1 4G/5G polymorphism is associated with metabolic syndrome parameters in Malaysian subjects.

The plasminogen activator inhibitor-1 4G/5G and tissue plasminogen activator Alu-repeat insertion/deletion polymorphisms might be genetic determinations of increased or decreased of their plasma activities. The aim of this study was to investigate the association of plasminogen activator inhibitor-1 4G/5G and tissue plasminogen activator Alu-repeat I/D polymorphisms with metabolic syndrome parameters in normal Malaysian subjects and to assess the impact of these polymorphisms on their plasma activities and antigens. The genetic polymorphisms were genotyped in 130 normal subjects. In addition, the plasma activities and antigens of plasminogen activator inhibitor-1 and tissue plasminogen activator as well as levels of insulin, glucose, and lipid profile at fasting state were investigated. The subjects with homozygous 4G/4G showed association with an increased triglyceride (p = 0.007), body mass index (p = 0.01) and diastolic blood pressure (p = 0.03). In addition, the plasminogen activator inhibitor-1 4G/5G polymorphism modulates plasma plasminogen activator inhibitor-1 activity and antigen and tissue plasminogen activator activity (p = 0.002, 0.014, 0.003) respectively. These results showed that, the plasminogen activator inhibitor-1 4G/5G polymorphism is associated with metabolic syndrome parameters, plasminogen activator inhibitor-1 and tissue plasminogen activator activities in Malaysian subjects, and may serve to increase the risk of type 2 diabetes and cardiovascular disease in Malaysian subjects.

KCNQ1 variants associate with type 2 diabetes in Malaysian Malay subjects.

INTRODUCTION: Type 2 diabetes (T2D) candidate gene: potassium voltage-gated channel, KQT-like subfamily, member 1 (KCNQ1) was suggested by conducting a genome wide association study (GWAS) in Japanese population. Association studies have been replicated among East Asian populations; however, the association between this gene and T2D in Southeast Asian populations still needs to be studied. This study aimed to investigate the association of KCNQ1 common variants with type 2 diabetes in Malaysian Malay subjects. MATERIALS AND METHODS: The KCNQ1 single nucleotide polymorphisms (SNPs): rs2237892, rs2283228, and rs2237895 were genotyped in 234 T2D and 177 normal Malay subjects. RESULTS: The risk allele of the rs2283228 (A) was strongly associated with T2D (OR = 1.7, P = 0.0006) while the rs2237892 (C) was moderately associated with T2D (OR = 1.45, P = 0.017). The recessive genetic models showed that rs2283228 was strongly associated with T2D (OR = 2.35, P = 0.00005) whereas rs2237892 showed a moderate association with T2D (OR = 1.69, P = 0.01). The haplotype block (TCA), which contained the protective allele, correlated with a protection from T2D (OR = 0.5, P = 0.003). Furthermore, the diplotype (CAA-TCA) that contained the protective haplotype was protected against T2D (OR = 0.46, P = 0.006). CONCLUSION: The KCNQ1 SNPs, haplotypes and diplotypes are associated with T2D in the Malaysian Malay subjects.

KCNQ1 haplotypes associate with type 2 diabetes in Malaysian Chinese Subjects.

The aim of this study was to investigate the association of single nucleotide polymorphisms (SNPs) and haplotypes of potassium voltage-gated channel, KQT-like subfamily, member 1 (KCNQ1) with type 2 diabetes (T2D) in Malaysian Chinese subjects. The KCNQ1 SNPs rs2237892, rs2283228 and rs2237895 were genotyped in 300 T2D patients and 230 control subjects without diabetes and metabolic syndrome. Two logistic regression models of analysis were applied, the first adjusted for age and gender while the second adjusted for age, gender and body mass index. The additive genetic analysis showed that adjusting for body mass index (BMI) even strengthened association of rs2237892, rs2283228 and rs2237895 with T2D (OR = 2.0, P = 5.1 × 10(-5); OR = 1.9, P = 5.2 × 10(-5); OR = 1.9, P = 7.8 × 10(-5), respectively). The haplotype TCA containing the allele of rs2237892 (T), rs2283228 (C) and rs2237895 (A) was highly protective against T2D (Second model; OR = 0.17, P = 3.7 × 10(-11)). The KCNQ1 rs2237892 (TT), and the protective haplotype (TCA) were associated with higher beta-cell function (HOMA-B) in normal subjects (P = 0.0002; 0.014, respectively). This study found that KCNQ1 SNPs was associated with T2D susceptibility in Malaysian Chinese subjects. In addition, certain KCNQ1 haplotypes were strongly associated with T2D.

Association of plasminogen activator inhibitor-1 and tissue plasminogen activator with type 2 diabetes and metabolic syndrome in Malaysian subjects.

BACKGROUND: Increased plasma plasminogen activator inhibitor-1 (PAI-1) activity and decreased tissue plasminogen activator (tPA) activity could be considered a true component of the metabolic syndrome (MetS) associated with an increased risk of developing cardiovascular diseases (CVD) and fibrinolytic abnormalities. The aim of this study was to investigate the association of tPA and its inhibitor PAI-1 with type 2 diabetes (T2D) and MetS and interrelationship between PAI-1 and tPA activities and antigens in Malaysian T2D and normal subjects. METHODS: The plasma activities and antigens of PAI-1 and tPA and the levels of the tPA/PAI-1 complex as well as serum insulin, parameter of the coronary risk panel and plasma glucose at fasting state were studied in 303 T2D subjects (227 with MetS and 76 without MetS), 131 normal non-diabetic non-metabolic subjects and 101 non-diabetic MetS subjects. RESULTS: The PAI-1 activity was higher in subjects with T2D with MetS (P = 9.8 × 10⁻¹9) and non-diabetic subjects with MetS (P = 3.0 × 10⁻¹5), whereas the tPA activity was lower in T2D with MetS (P = 0.003) as compare to normal subjects. Plasma tPA antigen levels were higher in subjects with T2D with MetS (P = 8.9 × 10⁻²4), T2D without MetS (P = 1.3 × 10⁻¹³) and non-diabetic MetS subjects (P = 0.002). The activity and antigen of PAI-1 in normal subjects were related to insulin resistance (P = 2.2 × 10⁻4; 0.007). Additionally, the PAI-1 activity was associated with an increased waist circumference (P = 2.2 × 10⁻4) and decreased HDL-c (P = 0.005), whereas the tPA activity was associated with decreased FBG (P = 0.028). The highest correlation was between PAI-1 activity and its antigen (R² = 0.695, P = 1.1 × 10⁻³6) in diabetic subjects. The tPA activity negatively correlated with its antigen (R² = -0.444, P = 7.7 × 10⁻¹³) in normal subjects and with the PAI-1 activity and antigen (R² = -0.319, P = 9.9 × 10⁻¹²; R² = -0.228, P = 3.4 × 10⁻6) in diabetic subjects. CONCLUSIONS: PAI-1 and tPA activities and antigens were associated with diabetes and MetS parameters in Malaysian subjects.