Screening Test Patch for Diabetic Autonomic Neuropathy

Impaired function of the sweat glands, or sudomotor dysfunction, is an early symptom of diabetic autonomic neuropathy (DAN). The detection of such a dysfunction can thus help diagnose diabetic polyneuropathy (DPN) before other typical sensomotoric and autonomic symptoms appear. The occurrence of autonomic neuropathy with sudomotor dysfunction is correlated with the occurrence of diabetic foot syndrome (DFS) and the development of cardiovascular autonomic neuropathy (CAN). A convenient test patch has been developed for the diagnosis of sudomotor dysfunction: the Neuropad (R). It is applied to the foot and measures the secretion of moisture by sweat glands, which is correlated with the cholinergic function. The test patch is applied like a sticking plaster to the foot and is therefore suitable for use by patients as a screening tool. Left on the foot for ten minutes, the patch indicates the presence of moisture from sweating by a colour change from blue to pink. Clinical trials showed that the patch test is an effective screening tool for DAN. In addition, it can be used to predict the risk of the patient developing DFS or CAN. The test designed to detect sudomotor dysfunction has therefore been included in a number of guidelines and best practices. In this publication, we present the latest findings concerning the test and its use, discuss the strengths and weaknesses of the test method and explore further possible applications.