Metformin was associated with more modest reports of pain among patients with lumbar radiculopathy.

In a retrospective case-control study presented at the annual meeting of the Endocrine Society, 46 patients who were taking metformin and sought care for lumbar radiculopathy pain averaged a 1.85-point lower score on a 0-10 point “having pain now,” scale as did 94 controls, 18 of whom had type 2 diabetes. The two groups were matched for their number of pain medications. None had peripheral neuropathy or other diabetic complications, reported Dr. Magdalena Szkudlinska of the University of Arizona, Tucson.

Mechanistic studies were conducted in animal models. Other researchers have identified AMPK (adenosine monophosphate–activated protein kinase) as a potential therapeutic target in chronic neuropathic pain conditions. The proposed mechanism involves activation of AMPK by metformin, with resultant inhibition of the mTOR (mammalian target of rapamycin) pathway leading to reduced sensory neuron excitability and decreased chronic neuropathic pain (Nat. Cell Biol. 2011;13:1016-23).

Moreover, Dr. Szkudlinska added, metformin has proved “remarkably effective” in reducing nociceptor sensitization and pain in animal models (Mol. Pain 2011 Sept. 21 [doi:10.1186/1744-8069-7-70]).

“We propose that these results, combined with the preclinical rationale, warrant a larger prospective study testing the effectiveness of metformin on chronic neuropathic pain,” she declared.

Her retrospective lumbar radiculopathy study was supported by the National Institutes of Health. She declared having no financial conflicts.