Effect of hyperglycemia on pain threshold in alloxan-diabetic rats

Insulin-dependent diabetes mellitus (IDDM) is associated with several complications, including painful diabetic neuropathy. Both animal and human investigations suggest an altered pain response in IDDM. 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 tail flick latency in alloxan-diabetic and control rats. In addition, tail flick latency was determined under conditions of both hyperglycemia and euglycemia in diabetic rats. Conditions of hyperglycemia resulted in a significant decrease in the tail flick latency of alloxan-diabetic rats. In contrast, tail flick latency was significantly increased in diabetic rats following normalization of blood glucose levels. It is concluded that elevated blood glucose levels contribute to a decrease in pain threshold in alloxan-diabetic rats.