Impact of Intermittent Fasting on Insulin Sensitivity and HbA1c Levels among Overweight Adults with Prediabetes

Background:Prediabetes is a rapidly growing metabolic condition that increases the risk of developing type 2 diabetes and cardiovascular complications. Lifestyle modification remains the primary preventive strategy. Intermittent fasting has recently gained interest for its potential to improve insulin sensitivity and glycemic control through meal-timing adjustments rather than strict caloric restriction(definition). However, limited evidence exists within South Asian populations who experience higher rates of insulin resistance at earlier ages. Objective:To evaluate the impact of a 12-week intermittent fasting regimen on insulin sensitivity and HbA1c levels among overweight adults with prediabetes. Methods:A quasi-experimental pre–post intervention study was conducted at Services Hospital Lahore from October 2024 to March 2025. Forty-two overweight adults aged 25–55 years with HbA1c 5.7–6.4% were enrolled, of whom 38 completed the study. Participants followed a daily 16-hour fasting window with an 8-hour eating period, maintaining usual dietary preferences. Fasting glucose, fasting insulin, HOMA-IR, and HbA1c were measured at baseline and week 12 using standardized laboratory protocols. Data were analyzed in SPSS 26 using paired t-tests with p < 0.05 as significance. Results:After 12 weeks, fasting glucose reduced from 111.6 ± 8.3 mg/dL to 102.3 ± 7.9 mg/dL, and fasting insulin declined from 15.9 ± 3.4 µIU/mL to 12.8 ± 3.1 µIU/mL. Mean HOMA-IR improved from 4.37 ± 1.00 to 3.23 ± 0.92. HbA1c decreased from 6.05 ± 0.19% to 5.78 ± 0.22%. All changes were statistically significant (p < 0.001). Mild temporary hunger was reported but no adverse events occurred. Conclusion:Intermittent fasting significantly improved insulin sensitivity and HbA1c in overweight adults with prediabetes, suggesting a practical, low-cost lifestyle strategy to delay progression to type 2 diabetes. Larger randomized trials with long-term follow-up are recommended. Keywords:Blood Glucose, Fasting, HbA1c, Insulin Resistance, Intermittent Fasting, Prediabetic State, Time-Restricted Feeding