Autonomic and Somatosensory Nerve Function After 2 Years of Continuous Subcutaneous Insulin Infusion in Type I Diabetes

Autonomic and somatosensory nerve function was studied in 24 insulin-dependent diabetic subjects (aged 29 ± 7 yrs, diabetes duration 8 ± 4 yr) randomly allocated to either continuous subcutaneous insulin infusion (CSII; n = 12) or unchanged conventional insulin therapy (CIT; n = 12). Measures of glycemic control and somatosensory and autonomic nerve function were comparable in the two groups at the start. Glycemic control was significantly improved in the CSII group throughout study, whereas it remained unchanged in the CIT group. In the CIT group, vibratory perception threshold (VPT) of the great toe and the medial malleolus deteriorated, as did heart rate variation (HRV) at rest, at deep breathing (.05 < P < .06), and at standing. In contrast, CSII patients retained their VPT and HRV. Comparison of nerve function alterations during the 2-yr trial showed better preservation in CSII than in CIT patients of VPT in the great toe (0.8 ± 1.7 vs. −1.4 ± 1.9 V, P < .01) and the medial malleolus (1.5 ± 2.9 vs. −1.4 ± 1.8 V, P < .05) and of HRV at rest (10 ± 24 vs. −13 ± 22 ms, P < .05) and at standing (−0.01 ± 0.13 vs. −0.15 ± 0.16 ms, P < .05). We conclude that intensified glycemic control can favorably influence parasympathetic and somatosensory nerve function in insulin-dependent diabetes mellitus.