Impact of Intermittent fasting on glycemic control in adults with Type 2 diabetes: A systematic review of randomized controlled trials

Title: Impact of Intermittent Fasting on Glycemic Control in Adults with Type 2 Diabetes: A Systematic Review of Randomized Controlled Trials

Background: Intermittent fasting (IF) has emerged as a popular dietary strategy for weight loss and metabolic health. Its role in improving glycemic control in individuals with type 2 diabetes mellitus (T2DM), however, is still being explored.

Methods: A systematic review of randomized controlled trials was conducted using PubMed,

following PRISMA 2020 Guidelines. Studies published between 1996 and 2024 were included if they evaluated intermittent fasting interventions in adults with T2DM and reported outcomes such as glycated hemoglobin (HbA1c) or fasting blood glucose. Seventeen randomized controlled trials met inclusion criteria, encompassing time-restricted eating, intermittent energy restriction, and 5:2 fasting protocols.

Results: Intermittent fasting was associated with improvements in glycemic control across several studies. Reductions in HbA1c were observed in multiple trials, with post-intervention values reaching as low as 6.3% in intervention groups. Fasting blood glucose decreased more in IF groups compared to controls in some studies, with reductions of approximately 10–20 mg/dL. Weight loss was consistently reported, with reductions ranging from 2 to 6 kg. Some studies also demonstrated decreased medication requirements and improved insulin sensitivity. However, findings were not uniform, with several trials showing similar outcomes between IF and continuous energy restriction. Intermittent fasting was generally well tolerated, though hypoglycemia risk was noted in insulin-treated individuals, highlighting the need for medication adjustment and monitoring.

Conclusion: Intermittent fasting appears to be a practical and effective dietary approach for improving glycemic control and promoting weight loss in adults with T2DM. While results are encouraging, variability in study design and duration underscores the need for larger, long- term trials to determine optimal fasting strategies and ensure safety, particularly in patients receiving insulin therapy.

Shaheen K. Kaplan, PharmD, MBA, is a Doctor of Medicine candidate at Avalon University School of Medicine, expected to graduate in 2027. She has completed her basic sciences and the United States Medical Licensing Examination Step 1 and is currently undertaking core clinical rotations in West Virginia. Prior to medical school, she held senior leadership roles in global medical affairs within the biopharmaceutical industry, contributing to scientific strategy, medical communications, and product development initiatives. Her academic interests include metabolic disease, diabetes management, and evidence-based medicine, with a focus on lifestyle interventions and their application in clinical practice.