Sympathetic skin response for early detection of type 2 diabetic peripheral neuropathy and nephropathy

Diabetic peripheral neuropathy (DPN) and diabetic nephropathy (DN) are common complications of type 2 diabetes mellitus (T2DM). Although nerve conduction studies (NCS) and sympathetic skin response (SSR) can detect DPN, the more sensitive method for early diagnosis remains unclear. Furthermore, whether DPN can be used as a predictor for diabetic nephropathy needs clarification.

We evaluated nerve conduction studies, sympathetic skin response, and the diabetic nephropathy indicator microalbuminuria (MAU) in 192 patients with type 2 diabetes mellitus and 50 healthy controls.

Patients with type 2 diabetes mellitus showed a lower sensory nerve conduction velocity (SCV), sensory active nerve potential (SNAP), motor nerve conduction velocity (MCV), and compound motor action potential (CMAP) than the controls on NCS. Abnormal rates for nerve conduction studies and sympathetic skin response were 75.0% and 83.3%, respectively, in patients with type 2 diabetes mellitus. Interestingly, 54.2% of patients with normal nerve conduction studies had an abnormal sympathetic skin response. Moreover, we found a positive correlation between sympathetic skin response and microalbuminuria for the first time. The abnormal rate of microalbuminuria was 53.8%, lower than that of abnormal nerve conduction studies or sympathetic skin response patients.

Sympathetic skin response is a more sensitive method than nerve conduction studies for the early diagnosis of diabetic peripheral neuropathy. Abnormal sympathetic skin response might serve as an indicator for early diabetic nephropathy. Additionally, diabetic peripheral neuropathy may occur earlier than diabetic nephropathy in the development of type 2 diabetes mellitus.