Evaluation of the Effectiveness of Local Insulin Injection in Type 2 Diabetic Patients with Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is the most com-mon type of peripheral nerve entrapment and is a significant cause of morbidity; this syndrome has a higher incidence in diabetic patients. It has been suggested that insulin has an effect on nerve regeneration similar to that of nerve growth factor (NGF). Hence we aim to evaluate the effectiveness of local insulin injection on the median nerve in patients with type 2 diabetes mellitus who have mild-to-moderate carpal tun-nel syndrome. We carried out a single-blind randomized controlled trial (RCT) study in 50 patients, using a simple sampling and a ran-dom allocation of these 50 patients, of whom 20 had bilateral mild-moderate CTS, into two groups; 35 women and 15 men, aged between 43 to 60 years old, resulting in 70 hands, were cate-gorized into two groups. At baseline, we injected NPH insulin (10 U) directly into the carpal tun-nel in group 1 and performed physiotherapy for the other group (group 2). Two weeks later, NPH insulin (10 U) was again injected into the carpal tunnel, while physiotherapy was continued for group 2. Electrodiagnostic studies were carried out for these both groups before and 4 weeks af-ter the last injection and physiotherapy, and pa-tients were followed up for 6 weeks. In both groups, decrement of distal mo-tor latency (DML) of the median nerves was sta-tistically significant, as was the increment of the sensory nerve conduction velocity. Also the dec-rement of pain, paresthesia, numbness, weak-ness/clumsiness and nocturnal awaking was sta-tistically significant in both groups; however there was no significant difference between two the groups. Local insulin injection is an effec-tive and safe treatment for carpal tunnel syn-drome in type 2 diabetic patients as physiother-apy.