Features of isolated post-challenge hyperglycaemia in Jamaican adults

Isolated post-challenge hyperglycaemia (IPH) can be defined as a two-hour plasma glucose concentration > or = 11.1 mmol/L with a fasting plasma glucose concentration < 7.0 mmol/L. The aim of this prospective study was to determine the prevalence of IPH in a cohort of Jamaican individuals, and to determine if simple clinical features may predict the presence and subsequent diagnosis of IPH. A cohort of 1694 adults aged 25-74 years without physician-diagnosed diabetes mellitus was randomly selected. An oral glucose tolerance test (OGTT) was performed. Anthropometry, blood pressure and lipid profiles were measured. The prevalence of undiagnosed diabetes mellitus by the 1999 World Health Organization criteria was 6.4%. IPH accounted for 24% of these cases and 1.4% of the entire population. Individuals with IPH were significantly older, with greater body mass index, waist-hip ratio, systolic blood pressure, fasting blood glucose, total cholesterol and LDL-cholesterol than individuals with normal glucose tolerance. Individuals with IPH were not significantly different from individuals with fasting plasma glucose levels > or = 7 mmol/L (i.e. fasting hyperglycaemia) in anthropometry or blood pressure. However, total cholesterol and LDL-C were significantly elevated in the IPH group. OGTT screening of individuals with impaired fasting glucose (i.e. 6.1-6.9 mmol/l) could reduce the IPH group by 50%. Reducing the threshold for fasting glucose to 5.6 mmol/L would correctly classify 87% of the population. We concluded that individuals with IPH have features of the metabolic syndrome, which can aid in selection for screening. OGTT screening of individuals with fasting glucose values of 5.6-6.9 mmol/l is needed to identify IPH.