Role of glycemic variability and lipids in the changes in cutaneous microcirculatory blood flow in patients with impaired glucose tolerance or type 2 diabetes

Abstract

Glycemic variability may play a role in diabetic microangiopathic complications. We recently showed that glycemic variability is more marked in nondiabetic obese patients with slightly elevated HbA1c levels. We aimed to examine the relations between glycemic variability and microcirculatory cutaneous blood flow (CBF) in patients with impaired glucose intolerance (IGT) or type 2 diabetes (T2D). We included 34 patients, 19 with IGT (HbA1c 5.1 ± 0.61%) and 15 with T2D on oral hypoglycemic treatments (HbA1c 7.1 ± 0.7%), with normal blood pressure and free of cardiovascular history. CBF (mean and standard deviation, SDCBF) was measured by laser doppler (Periflux®) on the forearm during 3 minutes, one hour after a standard breakfast including 75 g of carbohydrates. During the post-prandial period mean glucose was calculated and glycemic variability (standard deviation SDglucose, CONGA and J-index) evaluated during 3 hours after breakfast using CGMS. Lipids (HDL-cholesterol, LDL-cholesterol and triglycerides) were assayed. Compared with IGT patients, T2Ds had higher mean glucose, CONGA and J-indexes, and lower mean CBF and SDCBF (P < 0.03 to < 0.0001). In the total population, mean CBF correlated negatively with SDglucose and J-index (r = −0.41, P < 0.01; r = −0.34, P < 0.05, even after adjustment for age and BMI), but not with mean glucose. Mean CBF also correlated negatively with HbA1c (r = −0.40, P < 0.01). In multivariate analysis, mean CBF remained significantly correlated with SDglucose and J-index independently from HbA1c only in IGTs. Glucose parameters from CGMS correlated with LDL-C and triglycerides and negatively correlated with HDL-C (P < 0.002 to P < 0.0001). SDCBF correlated negatively with lipids but did not correlate with glucose parameters. Microcirculatory CBF is lower in T2Ds than in IGTs. Glycemic variability seems to play a greater role than mean glucose and long-term hyperglycemia on peripheral microcirculation, mostly in patients with IGT. Lipid parameters cluster with glycemic variability and are associated with lower vasomotricity.