Alpha-Lipoic Acid Improves Peripheral Insulin Sensitivity in Patients with Type 2 Diabetes

Abstract:

Alfa-lipoic (thioctic) acid is the only specificcally acting medicament in diabetic polyneuropathy treatment. Its impact on insulin resistance is not well enought clarified. In an open-label, randomized control trial the effect of thioctic acid (Thioctacid, ASTA Medica, Germany) on peripheral insulin sensitivity, glycemic control and cardiovascular risk markers in type 2 diabetic patients is studied. 12 adequately controlled patients (6 men; 6 women) at mean age 52,9 ± 9,9 y, BMI 33,99 ± 7,40 kg/m² and diabetes duration 4,8 ± 3,1 y, and 12 sex, age, BMI and study parameters matched subjects with normal glucose tolerance participate in the trial. Insulin sensitivity is assayed by a 2-h manual hyperinsulinemic euglycemic clamp (blood glucose level kept at 5 mmol/l, insulin infusion rate 40 mU/m²/min) and assessed as insulin mediated glucose disposal rate (M value) and insulin sensitivity index (ISI). Thioctacid at dose 1,2 g (2 tabl x 600 mg) is given twice daily over a 4-week period. At termination of study, insulin sensitivity is remarkably enhanced: M value from 3,202 ± 1,898 to 5,951 ± 3,402 mg/ kg/min (p  <0,05), and ISI – from 4,706 ± 2,666 to 7,673 ±3.559 mg/kg/min per mlU/1×100 (p < 0,05), with no statisticaly significant difference from that in controls. The levels of blood glucose (mean fasting blood glucose 5,919 ± 0,830 mmol/l and postprandial blood glucose 7,143 ±2,290 mmol/l) allowed reduction of the antidiabetic drug dose in 6 cases. Fasting serum insulin, uric acid, BMI and arterial pressure are irresponsive to treatment. No adverse effects are observed. In conclusion, thioctic acid may be considered as a drug of choice in treating type 2 diabetic patients because of its benefical effect on insulin resistance – a major cardiovascular risk factor.

Keywords: alfa-lipoic (thioctic) acid, insulin sensitivity, insulin resistance, type 2 diabetes mellitus.