An exploratory study of the association between KCNB1 rs1051295 and type 2 diabetes and its related traits in Chinese Han population

Since the KCNB1 encoding Kv2.1 channel accounts for the majority of Kv currents modulating insulin secretion by pancreatic islet beta-cells, we postulated that KCNB1 is a plausible candidate gene for genetic variation contributing to the variable compensatory secretory function of beta-cells in type-2 diabetes (T2D). We conducted two studies, a case-control study and a cross-section study, to investigate the association of common single-nucleotide polymorphisms (SNPs) in KCNB1 with T2D and its linking traits. In the case-control study, we first examined the association of 20 tag SNPs of KCNB1 with T2D in a population with 226 T2D patients and non-diabetic subjects (screening study). We then identified the association in an enlarged population of 412 T2D patients and non-diabetic subjects (replication study). In the cross-sectional study, we investigated the linkage between the candidate SNP rs1051295 and T2D by comparing beta-cell function and insulin sensitivity among rs1051295 genotypes in a general population of 1051 subjects at fasting and after glucose loading (oral glucose tolerance tests, OGTT) in 84 fasting glucose impaired subjects, and several T2D-related traits. We found that among the 19 available tag SNPs, only the KCNB1 rs1051295 was associated with T2D (P = 0.027), with the rs1051295 TT genotype associated with an increased risk of T2D compared with genotypes CC (P = 0.009). At fasting, rs1051295 genotype TT was associated with a 9.8% reduction in insulin sensitivity compared to CC (P = 0.008); along with increased plasma triglycerides (TG) levels (TT/CC: P = 0.046) and increased waist/hip (W/H) ratio (TT/CC: P = 0.013; TT/TC: P = 0.002). OGTT confirmed that genotype TT exhibited reduced insulin sensitivity by 16.3% (P = 0.030) compared with genotype TC+CC in a fasting glucose impaired population. The KCNB1 rs1051295 genotype TT in the Chinese Han population is associated with decreased insulin sensitivity and increased plasma TG and W/H ratio, which together contribute to an increased risk for T2D.

Risk factors and pain status due to diabetic neuropathy in chronic long-term diabetic patients in a Chinese urban population

BACKGROUND

With economic growth and urbanization there have been significant changes in the life style and diet of urban residents in large cities of China, which is experiencing a rapid increase in the prevalence of diabetes. While high prevalence of diabetes has been reported, little is known of the long-term effects of diabetes in such a large population. The aim of this study was to estimate the morbidity rate of diabetic peripheral neuropathy (DPN) in a Chinese urban diabetic population with more than 10 years' disease duration, and evaluate the relevant risk factors. The clinical manifestation of DPN and pain status was also assessed.

METHODS

Five hundred and sixty-five diabetes patients were recruited into the study. Symptoms and examination helped diagnose neuropathy. The clinical manifestation of DPN was assessed with a visual analog pain score (VAS). Diabetic complication status was determined from medical records. Serum lipids and lipoproteins, glycosylated hemoglobin (HbA1c), and the urinary albumin excretion rate were measured.

RESULTS

The morbidity rate of DPN was 46.6%. HbA1c, hyperlipidemia, and retinopathy were significantly associated with neuropathy, and these risk factors were correlated with other diabetic micro and/or macrovascular complications. The average VAS pain score of the DPN patients was 4.12 ± 2.07. Severe and moderate pain was experienced by 11.4% and 40.5% respectively of DPN patients. About 3.7% of diabetic subjects had lower limb ulcer or amputation.

CONCLUSIONS

The morbidity rate of DPN for diabetic patients with > 10 years duration is very high compared to the range reported for other populations in the world. The risk factors for DPN include HbA1c, hyperlipidemia, and retinopathy. In long-standing diabetic patients, DPN was not associated with diabetic duration, and half of the DPN patients experienced considerable daily suffering.