Identification of factors differentially associated with isolated impaired fasting glucose and isolated post-load impaired glucose tolerance: The Hong Kong Cardiovascular Risk Factor Study

Background: The use of fasting and post-prandial glucose levels in the classification of hyperglycaemic states often identifies distinct subjects, but the factors determining these intermediate-isolated glucose intolerant states are yet to be clearly elucidated in Chinese subjects. Methods: Representative subjects (n=2769) were randomly recruited from the Hong Kong Chinese population and glycaemic status was determined using both fasting and 2h 75 g oral glucose tolerance test glucose levels. The relationship between the groups with isolated glucose intolerance and vascular risk factors was investigated using ANOVA and logistic regression analyses. Results: Using either criterion, diabetes was identified in 265 (9.6%) subjects and glucose intolerance in 568 (20.5%) subjects. Of those 568, isolated impaired glucose tolerance (IGT) using the post-load criterion was identified in 49.5% and isolated impaired fasting glucose (IFG) in 30.5%. Ageing and hyperinsulinaemia were common determinants of IGT and IFG; with small hip circumference a marker of poorer early life development and being born in China rather than Hong Kong, a possible low birth weight marker was also associated with LFG. Hypertension, hypertriglyceridaemia and poor education were also associated with IGT. When we looked for factors differentially associated with these glucose intolerant states, female sex, greater hip circumference, high triglyceride levels, low fasting insulin levels, and not being born in China were independently associated with isolated IGT compared with isolated IFG. Conclusion: Despite common antecedents to the glucose intolerant states, isolated IFG appeared to be particularly associated with early life development, and isolated IGT was more strongly associated with obesity-related determinants such as hypertriglyceridaemia.