Metformin: Potential analgesic?

Objective To determine the association of self‐report use of metformin and pain intensity. Design Survey‐based cross sectional. Setting Primary care in an academic medical center. Subjects Three hundred and twenty nine participants with diabetes. Methods A total of 329 men and women, aged 18–65, completed a phone‐based survey. We utilized the Brief Pain Inventory to assess for pain intensity ratings; Leeds Assessment of Neuropathic Symptoms and Signs to screen for neuropathy; and the Personal Health Questionnaire (PHQ8) Depression Scale to assess for depression. Results Three hundred and twenty nine diabetics (mean age 54‐ ± 8‐year old) completed the study (162 metformin users, 167 nonusers). Compared with non‐users, metformin users were used more often [38% vs 20%, P  = 0.001]; had lower mean depression scores [6.8 vs 8.3; P  = 0.026] and fewer comorbidities [1.5 vs 1.8, P  = 0.022]. Adjusting for those three variables, pain scores were not significantly different between groups. In a subset analyses of those with neuropathic pain (n = 156), there were no differences in pain scores found between groups. Conclusions In a clinic sample of patients with diabetes, the use of metformin at an average dose of 1,432 mg (SD = 596 mg) was not associated with lower pain scores. Given the anti‐nociceptive effects of metformin in the animal models of pain, and the relative safety of metformin, future research should evaluate the effect of the higher dose of metformin as a potential analgesic.