Peripheral microvascular response to muscle contraction is unaltered by early diabetes but decreases with age.

Long-term or untreated diabetes leads to micro- and macrovascular complications. However, there are few tests to evaluate microvascular function. A postcontraction blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) technique was exploited to measure peripheral microvascular function in diabetics and healthy controls matched with respect to age, body mass index, and physical activity. Postcontraction BOLD microvascular response was measured following 1-s maximal isometric ankle dorsiflexion in individuals with diabetes mellitus type I [DMI, n = 15, age 33 ± 3 yr (means ± SE), median diabetes duration = 5.5 yr] and type II (DMII, n = 16, age 45 ± 2 yr, median duration = 2.4 yr); responses were compared with controls (CONI and CONII). Peripheral macrovascular function of the popliteal and tibial arteries was assessed during exercise hyperemia with phase contrast magnetic resonance angiography following repetitive exercise. There were no group differences as a result of diabetes in peripheral microvascular function (peak BOLD response: DMI = 2.04 ± 0.38% vs. CONI = 2.08 ± 0.48%; DMII = 0.93 ± 0.24% vs. CONII = 1.13 ± 0.24%; mean ± SE), but the BOLD response was significantly influenced by age (partial r = -0.384, P = 0.003), supporting its sensitivity as a measure of microvascular function. Eleven individuals had no microvascular BOLD response, including three diabetics with neuropathy and four controls with a family history of diabetes. There were no differences in peripheral macrovascular function between groups when assessing exercise hyperemia or the pulsitility and resistive indexes. Although the BOLD microvascular response was not impaired in early diabetes, these results encourage further investigation of muscle BOLD as it relates to peripheral microvascular health.