Tolrestat in the primary prevention of diabetic neuropathy

To compare the effects of tolrestat and placebo in patients with subclinical diabetic neuropathy.

Non-insulin-dependent diabetes mellitus (NIDDM) patients with early involvement of the autonomic nervous system were identified by only one pathological (outside the 99% confidence interval of the normal population) squatting test (vagal or sympathetic). Fifty-seven patients entered a randomized, placebo-controlled, double-blind, parallel 52-week study of tolrestat at a dose of 200 mg/day. Cardiovascular reflex tests (squatting vagal and sympathetic tests, pressure gain, deep breathing, lying-to-standing, Valsalva maneuver, and orthostatic hypertension), vibration thresholds, tendon reflexes, and muscle strength were assessed throughout the study.

At 12 months, nerve function significantly improved in patients receiving tolrestat and deteriorated in patients taking placebo. At baseline, the squatting vagal test was normal in 16 patients in the tolrestat group and in 15 patients in the placebo group. At 12 months, 25 patients taking tolrestat had a normalized squatting test, but only 6 patients taking placebo did (P = 0.02). Vibration perception threshold improved by a value of 6 +/- 3 V in the tolrestat group (P < 0.001) and deteriorated by a value of 3 +/- 1.8 V (P < 0.001) in the placebo group.

Tolrestat may be useful in the primary prevention of diabetic neuropathy.