Nighttime blood pressure, nighttime glucose values, and target-organ damages in treated type 2 diabetes patients

Objective: The associations between nighttime blood pressure (BP) and cardiovascular risk are well established. However, the associations between nighttime glucose values, including nocturnal hypoglycemia, and cardiovascular risk in diabetes remain unclear. Methods: In this cross-sectional study of 49 treated type 2 diabetes patients (mean, 67.3 years; 61.0% men; mean treatment duration, 9.4 years), we performed 24-h continuous glucose monitoring simultaneously with BP monitoring, and evaluated several target-organ damages (echocardiographic left ventricular mass index [LVMI], urinary albumin excretion [UAE], carotid-artery intima-media thickness [IMT], and brachial-ankle pulse wave velocity [baPWV]). Results: Nighttime average systolic BP values were independently associated with the extent of LVMI, log-transformed UAE, or baPWV (all P < 0.05). In contrast, nighttime average glucose values, rather than daytime glucose values or glucose variability, were independently associated with the extent of common carotid-artery IMT (CCA-IMT) or baPWV (all P < 0.05). We divided the study participants into 3 groups according to the nighttime glucose values (a group with nighttime average glucose values < 161 mg/dl [reference], a group with nocturnal hypoglycemia [< 70 mg/dl at least one point during sleep], and a group with nighttime average glucose values >= 161 mg/dl), and compared the extent of target-organ damages among them. Patients with nighttime average glucose values >= 161 mg/dl, but not those with nocturnal hypoglycemia, had the highest values of CCA-IMT or baPWV among the 3 groups, and the differences remained significant even after adjustment for covariates (both trend P < 0.05 by ANCOVA). Conclusions: Among treated type 2 diabetes, high nighttime BP and/or glucose values were associated with a high degree of cardiovascular remodeling. (C) 2013 Elsevier Ireland Ltd. All rights reserved.