Relationship between diurnal blood pressure variation and diurnal blood glucose levels in type 2 diabetic patients

Background: Hypertension and hyperglycemia are established risk factors for progression of microangiopathies and macroangiopathies in type 2 diabetes mellitus. Cardiovascular risk is even more increased in diabetic patients with nocturnal nondipping or postprandial hyperglycemia. We therefore investigated the relationship between diurnal hyperglycemia and diurnal blood pressure (BP) variation in patients. Methods: One hundred seven hypertensive type 2 diabetic patients received a 24-h ambulatory BP recording. In addition, a diurnal blood glucose profile was assessed under standardized conditions on the same day: before breakfast, 2 h after breakfast, before lunch, 2 h after lunch, before dinner, 2 h after dinner, at 10:00 PM, at midnight, and 3:00 AM of the following day. Degrees of fasting and postprandial hyperglycemia were calculated as area under the curve. Results: Nocturnal nondipping occurred in 73% of our patients. Nondippers showed higher postprandial blood glucose excursions than dippers (59.5 +/- 29 v 40.7 +/- 33 mmol h/L), whereas fasting hyperglycemia or glycosylated hemoglobin (HbA(1c)) were not significantly different (56.6 +/- 49 v 54.1 +/- 44 mmol h/L and 8.8% +/- 1.9% v 8.2% +/- 1.8% for nondippers and dippers, respectively). Nocturnal nondipping was associated with a higher urinary protein excretion and lower day/night heart rate ratio. Multivariate analysis revealed postprandial hyperglycemia as an independent predictor for nondipping. Conclusions: Postprandial rather than fasting hyperglycemia was associated with abnormal diurnal BP variation. These observations might favor treatment regimes targeted on postprandial hyperglycemia, which could restore dipping pattern.