Acute hyperglycaemia does not alter nitric oxide-mediated microvascular function in the skin of adolescents with type 1 diabetes

We assessed the impact of an acute bout of hyperglycaemia on nitric oxide (NO)-mediated microvascular function in the skin of adolescents with type 1 diabetes (T1DM).

Twelve subjects (12–18 years) with T1DM were randomised into a control (n = 6) or hyperglycaemia (n = 6) group. Hyperinsulinaemic clamps were used to manipulate blood glucose level (BGL). Following a baseline period, where all subjects were euglycaemic (20 min), the experimental phase began. During the experimental phase, BGL was elevated to 16.7 ± 0.9 mmol L⁻¹ in the hyperglyceamic group, while it was maintained at euglycaemia (5.5 ± 0.1 mmol L⁻¹) in the control group. Simultaneously, cutaneous microvascular function (% max cutaneous vascular conductance, CVC%) was assessed using laser Doppler fluxometry following stimulation of skin blood flow using localised heating (42 °C). To determine the NO contribution to skin blood flow, two microdialysis sites were assessed, one perfused with Ringers and the other with the NO blocker, NG-monomethyl-l-arginine (l-NMMA).

In the hyperglycaemic group, acute increase in BGL was not associated with changes in skin blood flow (CVC% 82.4 ± 8.7 % at 5.5 ± 0.1 mmol L⁻¹ vs 79.5 ± 9.1 % at 16.7 ± 0.9 mmol L⁻¹, unpaired t tests, P = 0.588) or the contribution of NO to vasodilation.

These results suggest that, in our group of adolescents with type 1 diabetes, acute hyperglycaemia did not affect skin microvascular NO-mediated function.