The Effect of Body Mass Index on Fasting Blood Glucose After Initiation of Thiazide Therapy in Hypertensive Patients

BACKGROUND: The prevalence of obesity, hypertension, and type 2 diabetes mellitus is increasing in the United States. In this setting, it is important to understand the effects of antihypertensives on glucose metabolism. We therefore examined the association between body mass index (BMI) (kg/m(2)) and fasting blood glucose (FBG) in subjects in whom thiazide antihypertensive therapy had been initiated. METHODS: A retrospective observational study was carried out on individuals with hypertension who had been started on thiazide therapy. The subjects' age, thiazide dose, BMI, serum potassium, FBG, new onset of diabetes mellitus, and concurrent use of other antihypertensives were included in the analysis. Predictors of change in FBG were analyzed using multiple linear regression analysis, while predictors of new-onset diabetes mellitus were determined using multiple logistic regression. RESULTS: A total of 2,624 individuals who had been started on thiazide therapy for hypertension were divided into quartiles of increasing BMI. FBG was found to be associated with baseline BMI and, after thiazide initiation, there was a step-wise increase in the magnitude of change in FBG with increasing BMI (P < 0.001 for both). Analysis using multiple linear regression found that BMI and baseline FBG predicted the magnitude of FBG change in subjects initiated on thiazide treatment (P < 0.001 for both). Analysis with logistic regression found that, after thiazide initiation, BMI, serum potassium baseline (P < 0.05 for both), and baseline FBG (P < 0.001) predicted the development of diabetes mellitus. CONCLUSIONS: There is an overall increase in FBG in individuals who are started on treatment with thiazides for hypertension. The magnitude of change in FBG and the development of new-onset diabetes mellitus after thiazide initiation were associated with increases in BMI and baseline FBG. American Journal of Hypertension (2008) doi:10.1038/ajh.2007.75American Journal of Hypertension (2008); 21 4. 438-442 doi:10.1038/ajh.2007.75.