Is HOMA index a predictor of nocturnal nondipping in hypertensives with newly diagnosed type 2 diabetes mellitus?

Objective Insulin resistance is involved in glucose intolerance, type 2 diabetes mellitus and hypertension. We aimed to analyze relationship between insulin resistance and nocturnal nondipping. Methods Patients underwent physical and biochemical evaluation, clinic and ambulatory blood pressure measurements. The homeostasis model assessment (HOMA) index was calculated. Results Ninety-six essential hypertensive patients, of whom 42 were dippers, with newly diagnosed type 2 diabetes mellitus were included. Nighttime average heart rate and mean arterial pressure of nondippers; were higher than dippers (P<0.0001 and 0.001). Nondippers had higher fasting plasma glucose, serum insulin levels and HOMA indices than dipper patients (P=0.006, <0.0001 and <0.0001). Ten dippers and 36 nondippers were insulin resistant (P<0.0001). Clinic Q= +0.22, P=0.031), daytime average (r= +0.27, P=0.007), nighttime average (r= +0.33, P=0.001), 24-h average systolic (r= +0.25, P= 0.015) and nighttime average diastolic blood pressures Q= +0.31, P=0.002) were positively correlated with homeostasis model assessment index. Nighttime mean arterial pressure and heart rates (daytime, nighttime, 24-h average) showed positive correlation with homeostasis model assessment index. In multivariate, analysis, high homeostasis model assessment index was associated with increased nondipping risk (odds ratio: 1.85, confidence interval: 1.24-2.76, P=0.003). After adjustment of several factors, average nighttime systolic (P<0.0001), diastolic (P<0.0001) and 24-h diastolic blood pressure (P=0.029) and heart rate (P=0.001) measurements of insulin resistant patients were higher than nonresistant patients. Conclusions Insulin resistance is related with diurnal blood pressure variation. The HOMA index may be a predictor of nocturnal nondipping in patients with essential hypertension and newly diagnosed type 2 diabetes mellitus.