Ethnic disparities in risk of cardiovascular disease, end-stage renal disease and all-cause mortality: a prospective study among Asian people with Type 2 diabetes.

AIM: To study prospectively the ethnic-specific risks of cardiovascular disease, end-stage renal disease and all-cause mortality in patients with Type 2 diabetes mellitus among native Asian subpopulations. METHODS: A total of 2337 subjects with Type 2 diabetes (70% Chinese, 17% Malay and 13% Asian Indian) were followed for a median of 4.0 years. Time-to-event analysis was used to study the association of ethnicity with adverse outcomes. RESULTS: Age- and gender-adjusted hazard ratios for cardiovascular disease in ethnic Malay and Asian Indian subjects were 2.01 (1.40-2.88; P<0.0001) and 1.60 (1.07-2.41; P=0.022) as compared with Chinese subjects. Adjustment for conventional cardiovascular disease risk factors, including HbA1c , blood pressure and lipid profile, slightly attenuated the hazards in Malay (1.82, 1.23-2.71; P=0.003) and Asian Indian subjects (1.47, 0.95-2.30; P=0.086); However, further adjustment for baseline renal function (estimated GFR) and albuminuria weakened the cardiovascular disease risks in Malay (1.48, 0.98-2.26; P=0.065) but strengthened that in Asian Indian subjects (1.81, 1.14-2.87; P=0.012). Competing-risk regression showed that the age- and gender-adjusted sub-distribution hazard ratio for end-stage renal disease was 1.87 (1.27-2.73; P=0.001) in Malay and 0.39 (0.18-0.83; P=0.015) in Asian Indian subjects. Notably, the difference in end-stage renal disease risk among the three ethnic groups was abolished after further adjustment for baseline estimated GFR and albuminuria. There was no significant difference in risk of all-cause mortality among the three ethnic groups. CONCLUSIONS: Risks of cardiovascular and end-stage renal diseases in native Asian subjects with Type 2 diabetes vary substantially among different ethnic groups. Differences in prevalence of diabetic kidney disease may partially explain the ethnic disparities.

High normal albuminuria is independently associated with aortic stiffness in patients with Type 2 diabetes.

BACKGROUND: High normal albuminuria is associated with higher cardiovascular risk in patients with diabetes. Increased aortic stiffness is an established risk factor of vascular events. However, the relationship between albuminuria within the normal range (0-30 mg/g) and aortic stiffness in patients with Type 2 diabetes is unknown. METHODS: A total of 614 normoalbuminuric subjects with Type 2 diabetes with spot urinary albumin:creatinine ratio ≤ 30 mg/g and estimated glomerular filtration rate ≥ 60 ml min⁻¹ 1.73 m⁻² were included in the study. Aortic stiffness was assessed by carotid-femoral pulse wave velocity. RESULTS: Pulse wave velocity increased progressively with the increase of albumin:creatinine ratio within the normoalbuminuric range (0-30 mg/g). Only 2.6% of the subjects with an albumin:creatinine ratio in the lowest quartile (0.7-3.4 mg/g) were classified as having aortic stiffness (pulse wave velocity ≥12 m/s). In contrast, the proportion of subjects with aortic stiffness increased significantly with the increase of albumin:creatinine ratio level (11.0%, 10.4% and 13.6% in albumin:creatinine ratio quartiles 2, 3 and 4, respectively, P = 0.008). A logistic regression model revealed that the odds of having aortic stiffness were increased by 56% with a 1-SD increase of log albumin:creatinine ratio after adjustment for age, gender, duration of diabetes, HbA1c , blood pressure, HDL and LDL cholesterol, estimated glomerular filtration rate, BMI, usage of renin-angiotensin system antagonists, statins and insulin. CONCLUSIONS: High normal albuminuria is associated with aortic stiffness in patients with Type 2 diabetes, which may in part explain their increased cardiovascular risk.

Adipocytokine zinc α2 glycoprotein (ZAG) as a novel urinary biomarker for normo-albuminuric diabetic nephropathy.

OBJECTIVE: A substantial proportion of diabetic nephropathy individuals are non-albuminuric. Using a proteomic approach, we searched for novel urinary biomarkers. METHODS: We studied three groups (n = 6 per group) of males with Type 2 diabetes: (1) normal renal function; (2) classical diabetic nephropathy (urinary albumin-creatinine ratio > 1000 mg/g and glomerular filtration rate < 60 ml/min.1.73 m(2) ) and (3) non-albuminuric diabetic nephropathy (glomerular filtration rate < 60 ml/min.1.73 m(2) and urinary albumin-creatinine ratio < 30 mg/g). We used two-dimensional fluorescence differential gel electrophoresis, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry peptide identification and western blot validation in the study. RESULTS: Sixty protein spots were differentially abundant between the non-albuminuric and macro-albuminuric subjects (> 2.5-fold, P < 0.05). In the non-albuminuric subjects, in addition to previously reported α(1) -microglobulin, the next most interesting spot (upregulated 3.44-fold, P = 0.0026) was human zinc-α(2) -glycoprotein, a novel adipose-cytokine associated with glomerular injury. This was confirmed by western blot and replicated in female diabetic nephropathy subjects. CONCLUSIONS: From our preliminary results, human zinc-α(2) -glycoprotein may be a novel urinary biomarker for non-albuminuric diabetic nephropathy.

Microarray analysis of multiple candidate genes and associated plasma proteins for nephropathy secondary to type 2 diabetes among Chinese individuals.

AIMS/HYPOTHESIS: Evolving research suggests that common and rare alleles jointly constitute the genetic landscape of complex disease. We studied the association between 43 pathway-related candidate genes with 'intermediate phenotype' (i.e. corresponding plasma protein) and diabetic nephropathy in a customised microarray of 1,536 SNPs. METHODS: In this case-control study of type 2 diabetic Chinese individuals with and without diabetic nephropathy, cases (n = 545) were defined on the basis of a spot urinary albumin/creatinine ratio (ACR) > 113 mg/mmol; the value for controls (n = 503) was ACR < 3.3 mg/mmol. Genotyping was performed using Illumina GoldenGate assay. RESULTS: No single nucleotide polymorphism (SNP) remained significant in single locus analysis after correction for multiple testing. Therefore, we explored the best approximately 1% SNPs. Of these 13 SNPs, four clustered to a 5' end NADPH oxidase homologue 4 (NOX4) haplotype (GGCC frequency = 0.776) with estimated OR for diabetic nephropathy of 2.05 (95% CI 1.04-4.06) (heterozygous) and 2.48 (1.27-4.83) (homozygous) (p = 0.0055). The haplotype was correlated with plasma Cu/Zn superoxide dismutase (SOD) concentration, suggesting increased oxidative burden. Endothelin-1 SNP (rs1476046G>A, frequency = 0.252) was correlated with plasma C-terminal pro-endothelin-1 concentrations with an estimated OR for diabetic nephropathy of (heterozygous) 1.26 (0.96-1.66) and (homozygous) 1.87 (1.13-3.12) (p = 0.0072). Nitric oxide synthase 1 (NOS1) 5' haplotype (TGTC frequency = 0.38) also revealed a suggestive association with diabetic nephropathy: heterozygous 1.26 (0.95-1.67), homozygous 1.57 (1.04-2.35) (p = 0.0073). A rare NADPH oxidase homologue 1 (NOX1)-coding non-synonymous SNP (Arg315His, frequency = 0.006) was found exclusively among cases. CONCLUSIONS/INTERPRETATION: Our preliminary observations suggest that common haplotypes from NOX4 and endothelin-1 SNP correlated with plasma Cu/Zn SOD and C-terminal pro-endothelin-1 concentrations, respectively, and might have conferred diabetic nephropathy susceptibility. Common NOS1 and rare NOX1 variants also revealed a suggestive association with diabetic nephropathy. Future studies to validate our observation are needed.

Lactate levels in Asian patients with type 2 diabetes mellitus on metformin and its association with dose of metformin and renal function.

AIM: Our aims are to discover the average fasting plasma lactate level (FPL) in Asian patients with type 2 diabetes mellitus on metformin, with or without renal impairment and whether FPL is associated with the total daily dose of metformin (Tmet) and the degree of renal impairment in these patients. METHODS: We conducted an observational cross-sectional study of Asian patients with type 2 diabetes, using measurements of FPL levels and glomerular filtration rate (GFR) calculated, using the abbreviated modification of diet in renal disease (MDRD) formula. The association between FPL, Tmet, GFR and other potential predictors was analysed. RESULTS: A total of 97 subjects were recruited from our diabetes centre between July 2005 and February 2006. Sixty (61.9%) of the subjects were males; 69 (71.1%) Chinese, 21 (21.6%) Malays and 6 (6.2%) Indians. The mean (SD) age was 58.8 years (10.7) and the mean body mass index was 27.1 kg/m(2) (5.3). The mean FPL was 1.8 mmol/l (0.9) with 20 (20.6%) of subjects having an FPL beyond the upper limit of our reference range of 2.2 mmol/l. The mean FPL (two SE) of subjects with Tmet of < or = 1000, 1001-2000 and > 2000 mg were 1.7 mmol/l (0.2), 1.6 mmol/l (0.2) and 2.1 mmol/l (0.5) respectively, (p = 0.119). The mean FPL of subjects with GFR of < 60, 60-90 and > 90 ml/min/1.73 m(2) was 1.7 mmol/l (0.3), 1.8 mmol/l (0.3) and 1.8 mmol/l (0.4) respectively, p = 0.757. Among the potential predictors analysed, aspartate transaminase (p = 0.001) was found to be significantly associated with FPL. CONCLUSIONS: Our study shows no correlation between Tmet and GFR with FPL in Asian type 2 diabetic patients on metformin.