Peripheral nerve function in patients with painful diabetic neuropathy treated with continuous subcutaneous insulin infusion.

In order to study the effects of improved metabolic control on painful diabetic polyneuropathy, 15 patients were treated with continuous subcutaneous insulin infusion over a 12 month period. Polyneuropathy was assessed by pain score, neurological examinations, nerve conduction studies and determination of sensory thresholds and cardiovascular reflexes. Improved metabolic control was confirmed by significantly improved levels of glycosylated haemoglobin (11.7 +/- 0.3% at entry to the study, to 8.7 +/- 0.3% after 12 months; mean +/- SEM). Symptomatic relief was confirmed by significantly improved pain scores. Thresholds for thermal cutaneous sensation improved significantly from 6.0 +/- 0.8 degrees C at entry to the study to 2.7 +/- 0.7 degrees C after 12 months (mean +/- SEM). These findings suggest a selective improvement of peripheral small nerve fibre function after continuous subcutaneous insulin infusion. The importance of quantitating thermal cutaneous sensation in longitudinal studies of patients with diabetic neuropathy was confirmed.