Correlation of peripheral nerve fatigue following vibratory stimulation with hyperglycemia in diabetic patients

To determine whether the vibratory perception threshold (VPT) was altered in patients with diabetes, we measured this parameter after 5 min of conditioning vibration in 59 patients with non-insulin-dependent diabetes mellitus (NIDDM), with (n = 36) and without clinical neuropathy (n = 23). Thirty-seven healthy volunteers served as controls. VPT in the diabetic patients was significantly correlated with fasting plasma glucose (FPG) level, but not with age. Although VPT increased in all three groups, the increase disappeared completely within 5 min in controls, but was sustained for over 5 min in the diabetic groups. delta-VPT, the difference between VPT 10 s after activation and the baseline VPT, was significantly larger in the diabetic groups than in the control group, and in diabetic patients, was closely correlated with FPG, but not baseline VPT or age. These findings indicate that VPT is markedly increased in diabetic patients following repetitive vibratory cutaneous stimulation and does not recover easily, perhaps as a result of defects in peripheral nerve excitability linked to glycemic control.