Validation of cooling detection threshold as a marker of sensorimotor polyneuropathy in type 2 diabetes

We aimed to validate the performance cooling detection thresholds (CDT) to detect diabetic sensorimotor polyneuropathy (DSP) in type 2 diabetes.

Two hundred and twenty participants with type 2 diabetes underwent clinical and electrophysiological examinations including 3 small fiber function tests: CDT, heart rate variability (HRV) and LDIFLARE. Clinical DSP was defined by consensus criteria whereas preclinical DSP was defined by presence of at least one electrophysiological abnormality. Area under the curve (AUC) and optimal thresholds were determined by receiver operating characteristic curves.

Participants were aged 63 ± 11 years with mean HbA1c of 7.5 ± 1.6%. The 139 (63%) clinical DSP cases had mean CDT values of 18.3 ± 8.9°C; the 52 (24%) preclinical DSP cases had 25.3 ± 3.5°C; and the 29 (13%) controls had 27.1 ± 3.8°C; (p-value<0.02 for all comparisons). For identification of clinical DSP cases, AUCCDT was 0.79 which exceeded AUCHRV (0.60, p=<0.0001) and AUCLDI FLARE (0.69, p=0.0003), optimal threshold <22.8°C (64% sensitivity, 83% specificity). Preclinical DSP AUCCDT was 0.80, also exceeding the other 2 measures (p<0.02 for both comparisons), optimal threshold ≤27.5°C (83% sensitivity, 72% specificity).

CDT had good diagnostic performance for identification of both clinical and preclinical neuropathy in type 2 diabetes. Its use as a non-invasive screening tool should be considered for research and clinical practice.