Mitigating Insulin Resistance in Taxi-Motorbike Drivers in Cotonou: Insights from Vitamin B12 and Lifestyle Factors

Background: Taxi-motorbike drivers (TMDs) in Cotonou are occupationally exposed to high levels of air pollution, which may contribute to metabolic dysfunction, including insulin resistance (IR). This study evaluated the associations between vitamin B12 levels, lifestyle factors, and IR in this high-risk population. Methods: A cross-sectional study was conducted among 139 TMDs in Cotonou, Benin. Fasting blood samples were collected to measure glucose, insulin, and vitamin B12 levels. Insulin resistance was assessed using HOMA-IR (>2.9). Participants were stratified by vitamin B12 quartiles, and logistic regression identified factors associated with IR. Results: The median age was 39.6 years (IQR: 34.0 - 44.0), and the median BMI was 22.8 kg/m2 (IQR: 20.8 - 25.8). IR prevalence was 67.6% (94/139), with a median HOMA-IR of 3.6 (IQR: 2.6 - 6.1). Vitamin B12 levels were adequate (>221 pmol/L) in 90.6% of participants. Participants in the third quartile (381 - 482 pM) had significantly lower glucose (4.1 nmol/L, p = 0.013), insulin (14.7 µM/mL, p = 0.014), and HOMA-IR (2.6, p = 0.009) compared to lower quartiles. Logistic regression identified BMI (OR = 1.28, 95% CI: 1.11 - 1.48, p = 0.001) and alcohol use (OR = 2.41, 95% CI: 1.02 - 5.72, p = 0.046) as risk factors for IR, while vitamin B12 levels between 381 - 482 pM were protective (OR = 0.19, 95% CI: 0.06 - 0.59, p = 0.004). Conclusions: This study reveals a high prevalence of IR among TMDs in Cotonou, with BMI and alcohol consumption identified as key modifiable risk factors. Notably, vitamin B12 levels within the 381 - 482 pM range, a moderate concentration exceeding standard deficiency thresholds, demonstrated a protective association against IR, potentially reflecting optimal bioavailability for mitigating oxidative stress and epigenetic dysregulation linked to air pollution exposure. Implementing tailored interventions to address nutritional and lifestyle factors, such as targeted vitamin B12 supplementation for TMDs with suboptimal levels (<381 pmol/L) and structured weight management programs, could reduce metabolic risks in this occupationally high-risk population.