The common C49620T polymorphism in the sulfonylurea receptor gene (ABCC8), pancreatic beta cell function and long-term diabetic complications in obese patients with long-lasting type 2 diabetes mellitus.

HYPOTHESIS: A gene polymorphism associated with accelerated beta-cell failure may lead to a more rapid development of long-term complications of type 2 diabetes (T2DM) due to a worse metabolic control of the disease. AIM OF THE STUDY: Evaluation of an association between the intronic C49620T (exon 16 -3c-->t) polymorphism in the ABCC8 (SUR1) gene and beta-cell function, as well as the prevalence of long-term diabetic complications in obese patients with long-lasting type 2 diabetes. METHODS: Two hundred and fifteen obese patients with at least a 10-year history of T2DM were thoroughly characterized clinically. In all the patients the intravenous glucagon test was performed and the C49620T ABCC8 polymorphism was assessed. Subgroups of patients, classified either according to genotype or to allele carriage, were compared. RESULTS: No difference was found between the groups in variables describing beta-cell function and the prevalence of chronic diabetic complications, with the exception of a significantly lower incidence of brain stroke in CC homozygotes than in patients carrying T allele (CT+TT). Body mass index was higher in patients carrying C allele than in TT homozygotes. HDL-cholesterol was higher in CT heterozygous than in homozygous CC or TT patients. CONCLUSIONS: There is no association between the ABCC8 polymorphism gene and the beta-cell function or the prevalence of chronic diabetic complications in obese patients with long-term T2DM, except for brain stroke. The results might suggest that the homozygous CC subjects are at lower risk of the complication, but additional studies are warranted to test this finding.

Association between the Pro12Ala variant of the peroxisome proliferator-activated receptor-gamma2 gene and increased 24-h diastolic blood pressure in obese patients with type II diabetes.

The aim of the study was to examine an association between the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor (PPAR)-gamma2 gene and blood pressure values assessed by 24-h ambulatory blood pressure monitoring (ABPM) in obese patients with long-lasting type II diabetes. Two hundred and fourteen obese patients (95 men and 119 women) with above 10-year history of type II diabetes were recruited for the study. In all the patients, ABPM was performed and other parameters, including age, body mass index (BMI), waist/hip ratio (WHR), haemoglobin A1c (HbA(1c)), serum lipids and creatinine were also evaluated. The Pro12Ala polymorphism was analysed by polymerase chain reaction-restriction fragment length polymorphism. Two subgroups of patients were compared: (a) Pro/Pro: homozygotic Pro/Pro (n=154) and (b) Ala: Ala allele carriers (Ala/Ala+Ala/Pro) (n=60). The studied groups were not different when age, BMI, WHR, HbA(1c), lipids, creatinine and frequency of hypertension were compared. A similar ratio of patients from both groups were treated with angiotensin-converting enzyme inhibitors, calcium channel blockers, diuretics, beta-blockers and alpha-blockers. A difference was observed in a mean 24-h (Ala: 71.9+/-8.1 vs Pro/Pro: 69.4+/-7.8 mm Hg, P=0.034) and a mean night time (Ala: 67.1+/-7.8 vs Pro/Pro: 64.5+/-8.4 mm Hg, P=0.025) diastolic blood pressure, which was significantly higher in patients with Ala variant. There was also a trend towards a higher mean daytime diastolic blood pressure in this group. It seems that the Pro12Ala variant is associated with an increased mean 24-h diastolic blood pressure in obese diabetic patients. Different reaction for antihypertensive medication depending on a variant of the PPAR-gamma2 gene should also be considered as a possible cause of the presented results.