Association between glycemic control and morning blood surge with vascular endothelial dysfunction in type 2 diabetes mellitus patients

OBJECTIVE: Morning blood pressure surge (MBPS) is an independent predictor of cardiovascular events. However, little is known about the association between glycemic control and MBPS, and its effect on vascular injury in patients with type 2 diabetes mellitus (T2DM). The current study examined the association between glycemic control and MBPS and the involvement of MBPS in the development of vascular dysfunction in T2DM patients. MATERIALS AND METHODS: One hundred and twenty-two consecutive T2DM outpatients from the Department of Cardiology and Endocrinology were enrolled in this study. We did MBPS in T2DM patients, 85 (male) (69.7%) patients and 37 (female) patients (30.3%); mean age 60.1 ± 9.39; (n = 122) using 24 h ambulatory blood pressure monitoring and assessed vascular function by brachial artery flow-mediated dilation (FMD) and nitroglycerin-mediated dilation (NMD). RESULTS: The correlation between MBPS and various clinical variables were examined by single regression analysis in all subjects. MBPS showed significant and positive correlation with pulse rate (P = 0.01), fasting blood sugar (P = 0.002), and postprandial blood sugar (P = 0.05). To further confirm the association of insulin resistance (IR) with MBPS in T2DM patients, we examined the correlation between homeostasis model assessment-IR (HOMA-IR), an established marker of IR and MBPS in diabetic (DM) patients who were not taking insulin no significant association with MBPS in T2DM patients (P = 0.41), angiotensin-converting enzyme/angiotensin receptor blocker (P = 0.07). We examined the relationship between MBPS and vascular injury by measuring endothelium-dependent FMD and endothelium-independent NMD in T2DM patients. Among the various traditional risk factors for atherosclerosis such as DM duration (P = 0.04), platelet reactivity (P = 0.04) and morning surge (P = 0.002) emerged as significant factors. HOMA-IR was a negative correlation with FMD. CONCLUSIONS: The current study demonstrated that poor glycemic control and IR have predictive value for the occurrence of MBPS in T2DM patients, which might be significantly associated with endothelial dysfunction.