Glycemic Control and Pain Threshold in Alloxan Diabetic Rats

Insulin dependent diabetes mellitus (IDDM) is associated with several complications including painful diabetic neuropathy. Previous animal and human studies have indicated that nociceptive thresholds are decreased by acute hyperglycemia. Furthermore, it has been suggested that glucose may be an important mediating factor in these painful symptoms. In the present study, pain threshold was assessed via the hot plate and formalin tests in control, untreated diabetic and treated diabetic rats. Hyperglycemia induced by 40mg/kg alloxan significantly lowered the pain threshold as revealed by a decrease in the hot plate latency and increased mean formalin score. In contrast, the hot plate latency was significantly increased and the formalin score significantly reduced in the diabetic rats following normalization of blood glucose level. These results suggest that hyperglycemic states contribute to a decrease in pain threshold in the alloxan diabetic rats.