Endocrine Abstracts

Aim: To evaluate the relationship between insulin resistance and cutaneous vasomotor responses (endothelial-dependent vasodilatation and peripheral sympathetic failure: noradrenergic control of smooth muscle cells – vasoconstriction and neuropeptides induced vasodilatation) in patients with metabolic syndrome (MS).

Methods and subjects: Patients with insulin resistance and MS (defined according to ‘The 2005 IDF definition of the metabolic syndrome’), but without hypertension were divided into two groups: 18 patients with type-2 diabetes mellitus (without insulin therapy and without pronounced diabetic complications) (DM) and 18 patients without DM. 18 healthy subjects were selected as controls (C). The study groups were matched for age and sex. Insulin resistance was measured by HOMA-IR method. We recorded changes in laser Doppler flux (LDF; PeriFlux 4001, Perimed) on the big toe. Basal LDF (b-LDF), postocclusive hyperemia (m₁-LDF), vasoconstrictor response (v-LDF) to deep inspiration on the pulp (apical skin); and heat (44 °C; PeriTemp 4005) induced hyperemia (m₂-LDF) on the dorsum (non-apical skin) of the big toe were estimated using a PeriSoft for Windows program.

Results: b-LDF and local skin temperature were without differences among the study groups (P>0.05). v-LDF was significantly less pronounced only in diabetics compared to healthy subjects (DM 31.8±13.7 vs C 52.6±8.5%, P<0.05). m₁-LDF was decreased in both patient groups in comparison with the controls (P<0.05), but the decrease of m₂-LDF was pronounced only in diabetics (DM 134±61 vs C 192±78 PU, P<0.05).

Conclusion: Our findings show that patients with insulin resistance have significant cutaneous vasomotor dysfunction despite the absence of pronounced diabetic or macrovascular complications.