The effect of dietary glycemic index and glycemic load on overweight individuals and type 2 diabetes patients: an overview of the literature

Introduction: Type 2 diabetes is increasing at an alarming rate worldwide. One of the leading factors to this condition is obesity. Low glycemic index (GI) and glycemic load (GL) diets have been proposed as lifestyle changes to address obesity, however, there is a lack of consensus on the optimal approach for weight loss, glycemic control and improving insulin sensitivity. In addition, the outcome of these diets are equivocal, with some studies suggesting beneficial outcomes and others suggesting otherwise. Furthermore, discrepant study designs have led to divergent conclusions. In order to provide a comprehensive overview of the low GI and low GL diets, a systematic review of literature on relevant observational studies and randomised control trials was performed on these databases:- The Cochrane Library, Medline, PubMed, Embase, Cinahl and Web of Science. Methods: The review was conducted based on the methodological standards for the conduct and reporting of Cochrane intervention reviews, Version 1.07, November 2018. Population, Intervention, Comparison and Outcomes (PICO) tool was used as the organising framework to define key elements of the review question. Results: Pertinent outcome variables include body weight, insulin resistance, HbA1c, fasting serum glucose, BMI, waist-to-hip ratio, triglyceride, HDL and LDL cholesterol. Our current understanding of these diets has been complicated by the reports that were based on different study designs and study populations. This review defines the issues, gaps in the research, study design, and evidence that is needed to inform practice, policy making and future research. There is also a dearth of information on the effect of low GI and GL diets on the Asian populations, specifically on improving insulin resistance. High carbohydrate diets are a mainstay of Asian societies. Conclusion: As cases of obesity and type 2 diabetes surge, there is an urgent need for research on low GI and GL dietary modifications among the Asian populations