Effect of Fructose Intake on Metabolic Biomarkers in Adults with Type 2 Diabetes Mellitus: A Systematic Review of Randomized Clinical Trial Studies

Introduction: Fructose is a lipogenic monosaccharide affecting glucose homeostasis and other metabolic biomarkers; however, there is conflicting evidence in this regard. The current systematic review aimed to determine the effects of fructose on metabolic biomarkers in individuals with T2DM using randomized clinical trial studies. Materials and Methods: In this systematic review study, after searching the PubMed, Science Direct, and Google Scholar databases using some keywords (namely fructose, type 2 diabetes, and metabolic biomarkers), 14 clinical trials related to the objectives of the present study, which were published from 1985 to 2020, were collected and reviewed. Results: Studies showed that fructose in patients with diabetes may reduce fasting and postprandial blood sugar, hemoglobin A1c, insulin resistance, and fructose amine. In interventions with fructose,  the concentrations of total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), lactate, pyruvate, and C-peptide remain unchanged. The findings of most of the reviewed articles indicated that the serum triglyceride concentration remained constant after fructose consumption. There is no clear evidence on the effects of fructose on blood pressure, plasma insulin concentrations and glucagon. Also, most of the findings showed no potential change in anthropometric variables. Conclusion: The findings of some studies have indicated a slight decrease in fasting blood sugar following fructose consumption. However, since these studies had a small sample size and a short intervention period and also used small amounts of fructose for intervention, using fructose in the food industry and in the diet of diabetics is not recommended. Further studies are needed to include this nutrient in diets.