Prevalence of distal symmetrical polyneuropathy by Diabetes Prevention Program treatment group, diabetes status, duration of diabetes, and cumulative glycemic exposure
Objective: To assess associations between distal symmetric polyneuropathy (DSPN) and Diabetes Prevention Program (DPP) treatment groups, diabetes status or duration, and cumulative glycemic exposure approximately 21 years after DPP randomization.
Research Design and Methods: In DPP, 3,234 adults ≥25 years old at high risk for diabetes were randomized to intensive lifestyle (ILS), metformin, or placebo interventions to prevent diabetes. After DPP, 2,779 joined the DPP Outcomes Study (DPPOS). Open label metformin was continued, placebo was discontinued, ILS was provided as semi-annual group-based classes, and all were offered quarterly lifestyle classes. Symptoms and signs of DSPN were assessed in 1,792 participants at DPPOS Year 17. Multivariable logistic regression models evaluated DSPN associations with treatment group, diabetes status/duration, and cumulative glycemic exposure.
Results: Twenty-one years after DPP randomization, 66% had diabetes. DSPN prevalence did not differ by initial DPP treatment assignment (ILS 21.5%, metformin 21.5%, and placebo 21.9%). There was a significant interaction between treatment assignment to ILS and age (p<0.05) on DSPN. At DPPOS Year 17, the OR for DSPN comparing ILS to Placebo was 17.4% (95% CI 3.0% - 29.3%) lower with increasing 5-year age intervals. DSPN prevalence was slightly lower for those at risk for diabetes (19.6%) versus those with diabetes (22.7%) and was associated with longer diabetes duration and time-weighted HbA1c (p-values<0.001).
Conclusions: The likelihood of DSPN was similar across DPP treatment groups, while higher for those with diabetes, longer diabetes duration, and higher cumulative glycemic exposure. ILS may have long-term benefits on DSPN for older adults.