Evaluation of effectiveness of local insulin injection in non-insulin-dependent diabetic patient with carpal tunnel syndrome.

Background: Carpal tunnel syndrome (CTS) is the most common type of peripheral nerve entrapment and is a significant cause of morbidity. Carpal tunnel syndrome (CTS) has more incidences in diabetic patients. It has been suggested that insulin has an effect on nerve regeneration similar to that of nerve growth factor (NGF). Therefore, we aimed to evaluate the effectiveness of local insulin injection on the median nerve in patients with non-insulin-dependent diabetes mellitus (NIDDM) who have mild-to-moderate carpal tunnel syndrome (CTS).

Materials and methods: We carried out a prospective, randomized, single-blind, case-controlled study in these patients. We randomly selected 50 patients, 20 of whom had bilateral mild-moderate CTS. Therefore we had 70 hands and categorized them into two groups. At the baseline we injected NPH insulin (10U) directly into the carpal tunnel in group 1, and performed physiotherapy for the other group (group 2). Two weeks later, NPH insulin (10U) was injected into the carpal tunnel again and we continued physiotherapy for group 2. Electrodiagnostic study was performed for these two groups before treatment and 4 weeks after the last injection and physiotherapy. The patients were followed up for 6 weeks.

Results: In both groups decrement of distal motor latency (DML) of the median nerves statistically was significant. In both groups, the increment of the sensory nerve conduction velocity was statistically significant. Also the decrement of pain, paresthesia, numbness, weakness/clumsiness and nocturnal awaking was statistically significant in both groups. But there was no significant difference between the two groups.

Conclusion: Local insulin injection is an effective and safe treatment for carpal tunnel syndrome in NIDDM patients as physiotherapy