Effects of serum triglyceride on islet β cell function and insulin resistance in patients with newly diagnosed gestational diabetes mellitus

Abstract

Objective To explore the effects of serum triglyceride on islet β cell function and insulin resistance in patients with newly diagnosed gestational diabetes mellitus(GDM). Methods Total of 439 newly diagnosed GDM patients at 24-30 weeks of gestation from maternity ward in First People's Hospital were recruited from January 2012 to April 2014. The demographic data, lipid profiles were collected and 75 g oral glucose tolerance test(OGTT)and insulin release test were performed. Homeostasis model assessment for β cell function index(HOMA-β), homeostasis model assessment for insulin resistance index(HOMA-IR)and quantitative insulin-sensitivity check index(QUICKI)were calculated respectively. The participants were divided into three groups based on the three tertiles of their fasting serum triglycerides: lowest tertile group(1.25-2.30 mmol/L, Group T1, n=146), medium tertile group(>2.30-3.10 mmol/L, Group T2, n=146)and highest tertile group(>3.10-22.03 mmol/L, Group T3, n=147). The data were analysed by one-way Anova method and multiple stepwise linear regression model was used to explore the risk factors which affected HOMA-IR in newly diagnosed GDM patients. Results Compared with that of Group T1, maternal body mass index(BMI)in Group T2 and T3 were signifcantly higher(both P< 0.05); total cholesterol(TC)level in Group T3 increased obviously and TG levels in Group T2 and Group T3 were significantly higher(all P<0.05); High density lipoprotein-cholesterol(HDL-C)level in Group T3 was lower, fasting plasma glucose(FPG)level and 1 h postprandial plasma glucose(1 hPG)level in Group T3 were higher(all P<0.05); fasting insulin(FINS)level in Group T2 and T3, 1 hINS level in Group T3, 2 h postprandial insulin(2 hINS)level in Group T2 and T3 were all elevated significantly(all P<0.05). Meantime, compared with that of Group T1, maternal HOMA-IR in Group T2 and T3 were elevated obviously (2.0±1.3, 2.7±1.2, 3.3±2.7 respectively, F=16.745, P<0.05), and maternal QUICKI in Group T2 and T3 decreased significantly(1.5±0.5, 1.2±0.4, 1.1±0.4 respectively, F=21.110, P<0.05). However, HOMA-β of three groups were almost at the same level. The multiple stepwise linear regression analysis indicated that BMI(standardized coefficient β =0.210), TG(β =0.135), 2 hINS(β =0.394)and age(β =-0.118)were significantly associated with HOMA-IR in newly diagnosed GDM patients(all P<0.05). Conclusions For the newly diagnosed GDM patients, insulin resistance worsens and insulin sensitivity reduces following the elevated fasting serum levels of triglyceride. Except increased BMI, higher 2 hINS level and younger age, higher TG level is independent risk factor for insulin resistance in those patients. Key words: Diabetes, gestational; Triglycerides; Insulin resistance; Islet β cell function