Two-hour glucose predicts the development of hypertension over 5 years: the AusDiab study

Elevated 2-h plasma glucose concentration (2hPG) from an oral glucose tolerance (OGTT) test more strongly predicts risk of subsequent cardiovascular disease than fasting plasma glucose (FPG), but the association between these glucose measurements and hypertension risk is less clear. We examined the association between 2hPG, FPG and risk of hypertension. We conducted a prospective observational study (The Australian Diabetes, Obesity and Lifestyle Study-AusDiab) among 4413 Australian residents who attended a baseline (1999 2000) and follow-up (2004-2005) examinations. Measurements included blood pressure (mean of two readings), 75 g OGTT, fasting insulin, anthropometrics, dietary and alcohol intake, medical history and physical activity. Hypertension was defined as a systolic blood pressure (SBP)>= 140 or a diastolic blood pressure (DBP)>= 90mm Hg or treatment with medication for hypertension. HOMA-S was calculated as a measure of insulin sensitivity using the HOMA2 calculator. Hypertension developed in 14% of the 4306 subjects available for this analysis. Higher 2hPG was significantly related to greater risk of hypertension after adjustment for age, gender, FPG, BMI (baseline and difference), waist circumference (baseline and difference), education, exercise, alcohol intake, baseline SBP and smoking (OR (95% CI) 1.12 (1.01 to 1.23)), but no significant association was seen between FPG and hypertension in this model (1.02 (0.88-1.19)). Further adjustment for HOMA-S did not change these findings. Higher baseline 2hPG was more strongly associated with an increase in SBP than in DBP over 5 years. We conclude that higher 2hPG predicted future hypertension occurrence in this population.