Excessive purine degradation during semi-ischemic forearm test in patients with diabetes mellitus

Abstract

Objective. The aim of this study was to investigate whether or not the purine degradation in the skeletal muscle during forearm exercise is augmented in patients with diabetes mellitus (DM). Methods. We used the semi-ischemic forearm test to examine the release of lactate (ΔLAC), ammonia (ΔAmm) and hypoxanthine (ΔHX) before exercise, 0, 4, 10, and 60 minutes after exercise in eleven diabetic patients and seven normal controls. Results. The sum of the increased HX (DM vs Controls: 26.1±21.2 vs 7.8±5.9 μmol/l, p<0.05) was greater in diabetic patients. When patients were divided into the excessive response group (n=7) and normal response group (n=4), the maximum increments in ΔHX and Δ Amm in the excessive response group (16.8±3.2 μmol/l and 122±60 μmol/l) were greater (p<0.05) than those in the control group (3.6±3.0 μmol/l and 32±34 μmol/l) and the normal response group (2.9±2.9 μmol/l and 27.4±12.7 μmol/l). ΔLAC both in the excessive response group (5.4±1.5 mmol/l) and the normal response group (3.6±1.0 mmol/l) were higher (p<0.05) than that of the control group (1.7±0.5 mmol/l). The prevalence of diabetic retinopathy was higher in the excessive response group than in the normal response group (75% vs. 25%). Conclusion. These data suggest that patients with DM, especially with microangiopathy have augmented purine degradation during the semi-ischemic forearm test. Factors responsible for the augmented purine degradation in these patients remain to be determined.