Insulin Resistance and Blood Pressure Circadian Variation in an Obese Hypertensive Population

Insulin resistance (IR) is related to arterial hypertension and target organ damage. Hypertensive individuals exhibiting a diminished nocturnal blood pressure (BP) reduction (non-dippers) have an increased incidence of cardiovascular events. The association, however, of IR with BP circadian variation has not been evaluated so far. Therefore, this study examined 226 (116 male and 110 female) overweight and obese subjects (BMI > 27kg/m2) with newly diagnosed essential hypertension who underwent clinical and laboratory evaluation, including an oral glucose tolerance test and ambulatory BP measurement (ABPM). IR was estimated using the homeostasis model assessment (HOMA-IR). The population was grouped according to HOMA-IR values > 2.75 (insulin resistance type) or < 2.75 (insulin sensitive type). Results. No significant differences were observed between dippers (n = 137) and non-dippers (n = 89) with respect to age, gender, BMI, serum cholesterol, triglycerides, LDL-C, and HDL-C levels, nor smoking habits. The proportion of IR subjects among dippers (59.1%) and non-dippers (56.7%) was similar (p = 0.833). Moreover, no significant association was found when the HOMA-IR was examined as a continuous component (p = 0.96). Conclusions. Insulin resistance is not associated with nocturnal blood pressure reduction in obese hypertensives. This may be explained by the notion that insulin secretion does not follow a circadian mode of variation.