Ultrasound-guided insulin injection for carpal tunnel syndrome in type 2 diabetes mellitus patients

Objective To compare effectiveness of ultrasound-guided local insulin injection, local steroid injection, and local steroid followed by insulin injections in treating mild to moderate carpal tunnel syndrome (CTS) in type 2 diabetes mellitus (DM). Method Study included 60 patients with electrophysiologic evidence of mild to moderate CTS. They were randomly divided into three groups: group I received insulin injection locally into the affected carpal tunnel at first visit and a similar dose after 2 weeks; group II received single injection of 40 mg methylprednisolone acetate injection; and group III received steroid injection then followed by insulin injection twice after 2 and 4 weeks. All injections were performed with ultrasonographic guidance. All patients were assessed by modified Boston Carpal Tunnel Questionnaire (FD score), CTS severity score (SS score), and neurophysiological and ultrasonographic assessments at baseline and 10 weeks after treatment. Results A significant improvement in mean FD score, SS score, DML (distal motor latency), SNCV (sensory nerve conduction velocity), PSL (peak sensory latency), Samp (sensory amplitude), and CSA (cross-sectional area of median nerve) observed in all groups (with exception of mean DML and Samp in the second group and mean Samp in the third group). Group III showed significant improvement in CSA especially when compared to group II by post hoc analysis (P = 0.005). Conclusions Local insulin injection is as effective as steroid in treating mild to moderate CTS in type 2 DM and is a safer alternative. Adding insulin injections after steroid shows more sonographic improvement than steroid alone.