Evaluation of HbA1c and Insulin Resistance-Related Measures in IT Employees With Shift Work Patterns: A Cross-Sectional Study

Background and objective: Shift work can disrupt circadian alignment and often coexists with sedentary behavior, irregular sleep, and altered meal timing.Information technology (IT) employees working night or rotating schedules may therefore be vulnerable to early metabolic dysfunction.This study compared glycated hemoglobin (HbA1c), fasting glucose, fasting insulin, and insulin resistance-related measures between shift-working and non-shift-working IT employees and described accompanying adiposity, lipid, physical activity, and sleep profiles.Methodology: This workplace-based analytical cross-sectional study included 400 IT employees in Chennai, India, between February and May 2025: 200 shift workers and 200 non-shift workers.Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), and physical activity was assessed using the International Physical Activity Questionnaire-Short Form (IPAQ-SF).The prespecified primary outcomes were HbA1c and fasting serum insulin.The group-level Homeostatic Model Assessment of Insulin Resistance using the original HOMA1 model (HOMA1-IR) index was included as a descriptive supporting insulin-resistance-related measure.Secondary outcomes included fasting plasma glucose, lipid profile, body mass index (BMI), waist circumference, waist-to-hip ratio, total physical activity <600 MET-min/week, PSQI global score, and poor sleep quality.Results: Shift workers had higher mean BMI (27.1 ± 3.4 vs. 24.6 ± 3.1 kg/m²) and waist circumference (94.8 ± 9.2 vs. 88.3 ± 8.5 cm).They also had higher fasting plasma glucose (104.2 ± 10.1 vs. 96.5 ± 8.8 mg/dL; mean difference 7.70 mg/dL, 95% confidence interval (CI) 5.84-9.56),fasting serum insulin (18.5 ± 6.2 vs. 11.3 ± 3.9 µIU/mL; mean difference 7.20 µIU/mL, 95% CI 6.18-8.22),and HbA1c (6.1 ± 0.4% vs. 5.5 ± 0.3%; mean difference 0.60 percentage points, 95% CI 0.53-0.67).The descriptive group-level HOMA1-IR index was numerically higher in shift workers (4.76) than in non-shift workers (2.69).Shift workers also had a less favorable lipid profile, a greater proportion with total physical activity <600 MET-min/week (61.0% vs. 47.0%;prevalence ratio 1.30, 95% CI 1.08-1.56;P = 0.005), and a higher prevalence of poor sleep quality (68.0% vs. 34.5%;prevalence ratio 1.97, 95% CI 1.59-2.44;P < 0.001).Conclusions: Shift-working IT employees demonstrated a less favorable metabolic and sleep profile, including higher fasting insulin and HbA1c and a numerically higher descriptive group-level HOMA1-IR index, consistent with a greater insulin-resistance-related burden.The cross-sectional design precludes causal inference, and the group-level HOMA1-IR estimate should not be interpreted as an individual diagnostic measure.These findings support occupational strategies addressing metabolic risk, sleep quality, physical activity, and recovery from night work.