The new indicator test (Neuropad): a valuable diagnostic tool for small-fiber impairment in patients with type 2 diabetes.

Purpose The purpose of this study was to evaluate the new indicator test for sudomotor function (Neuropad®) in the diagnosis of small-fiber impairment in patients with type 2 diabetes. Methods This study included 123 patients with type 2 diabetes (59 men; mean age, 64.3 ± 8.6 years; mean diabetes duration, 12 ± 6.1 years). Sudomotor dysfunction was assessed by means of the new indicator test. Neuropathy was diagnosed by the Neuropathy Disability Score and small-fiber impairment by temperature perception (Tiptherm device) and pain perception (Neurotip). Results The frequency of sudomotor dysfunction was significantly (P =.001) higher in patients with neuropathy (95%) than in those without neuropathy (30.2%). Sensitivity of the indicator test for neuropathy was 95%, and specificity was 69.8%. Frequency of neuropathy was significantly (P =.018) higher with the indicator test (74.8%) than with conventional clinical examination (65.4%). Sudomotor dysfunction was significantly (P =.001) more frequent in patients with small-fiber impairment (99%) than in those without small-fiber impairment (21.7%). Sensitivity for small-fiber impairment was 99%, and specificity was 78.3%. There was no difference (P =.999) in the frequency of small-fiber impairment as diagnosed with the indicator test (80.5%) and with clinical examination (81.3%). Conclusions The indicator test has a very high sensitivity and specificity for small-fiber impairment in patients with type 2 diabetes.