<![CDATA[Background: Diabetic peripheral neuropathy (DPN) is associated with older age and an abnormal ankle-brachial index (ABI). However, no previous study has investigated the synergistic interaction between older age and an abnormal ABI in relation to DPN.Purpose: This study aimed to investigate the independent associations and synergistic interaction of older age and an abnormal ABI in relation to DPN.Methods: This analytical cross-sectional study included 416 individuals with type 2 diabetes mellitus in Jakarta, Indonesia. Older age was defined as age >64 years. DPN was assessed using a combination of sensory testing with a 10-g Semmes-Weinstein monofilament and vibration testing with a 128-Hz tuning fork, with the diagnosis validated by a physician. ABI was assessed using continuous-wave Doppler ultrasound. Chi-square tests, independent t-tests, and multivariable logistic regression were performed with a significance level of p <0.05.Results: DPN was identified in 34.9% (n = 145) of participants. Older age (adjusted odds ratio [AOR] = 1.74) and an abnormal ABI (AOR = 2.04) were independently associated with DPN. Older participants with an abnormal ABI were 4.03 times more likely to have DPN than adult participants with a normal ABI (p < .001). A positive synergistic interaction between older age and an abnormal ABI in relation to DPN was identified (AOR = 4.03; relative excess risk due to interaction [RERI] = 2.20; attributable proportion [AP] = 0.55; synergy index [SI] = 3.65).Conclusion: Older age and an abnormal ABI were independently and significantly associated with DPN. Older participants with an abnormal ABI showed the most substantial synergistic effect on DPN. These findings highlight the importance of considering age and vascular status in T2DM. Routine ABI assessment, particularly in older adults, may help identify those at greater odds of DPN and guide targeted preventive care.]]>
