Chronic pain and type 2 diabetes: associations between neuropathic and nociplastic pain conditions, health behaviors, and mental health in veterans.

Pain is common in T2D; however, the differential impact of specific types of chronic pain (i.e., diabetic peripheral neuropathy; DPN and chronic overlapping pain conditions; COPCs) on T2D outcomes is unclear. Understanding these differences may provide insight into shared mechanisms and treatment targets. Aims were to (1) Evaluate the association of COPCs with T2D in Veterans, and (2) evaluate if chronic pain conditions (DPN and COPCs) are associated with worse health behavior and mental health outcomes in Veterans with T2D. This was a retrospective observational cohort study with Million Veteran Program participants. For Aim 1 (N = 342,000), logistic regression was used to assess the associations between T2D and eight COPCs based on electronic health record diagnoses. For Aim 2 (N = 103,222), individuals with T2D were categorized into four groups: (1) no COPCs or DPN (reference), (2) DPN only, (3) COPCs only, and (4) both COPCs and DPN. Outcomes included alcohol intake, smoking, physical activity, sleep, pain rating, A1C, major depressive disorder (MDD), and posttraumatic stress disorder (PTSD). All COPCs were associated with increased odds of T2D (AORs 1.23 [migraine]–1.64 [fibromyalgia]). Among Veterans with T2D, the COPC and DPN group had the highest odds of reporting high pain levels (AOR 1.67, 95%CI [1.58–1.76]), sleep concerns (AOR 1.63, 95%CI [1.50–1.77]), MDD (AOR 2.36, 95%CI [2.24–2.49]), and PTSD (AOR 2.29, 95%CI [2.17–2.43]). Both the DPN-only group (AOR 1.93, 95%CI [1.82–2.06]) and the COPC and DPN group (AOR 1.69, 95%CI [1.55–1.83]) had higher odds of an A1C > 8%, while the COPCs-only group had lower odds of A1C > 8%. COPCs are more common among Veterans with T2D and are associated with psychiatric disorders and sleep concerns. When co-occurring with DPN, COPCs may exert an additive toll on well-being. Findings support future research to evaluate underlying mechanisms and develop interdisciplinary treatments.