title: The effect of macronutrients on glycaemic control: a systematic review of dietary randomised controlled trials in overweight and obese adults with type 2 diabetes in which there was no difference in weight loss between treatment groups.
abstract: Weight loss is crucial for treating type 2 diabetes mellitus (T2DM). It remains unclear which dietary intervention is best for optimising glycaemic control, or whether weight loss itself is the main reason behind observed improvements. The objective of this study was to assess the effects of various dietary interventions on glycaemic control in overweight and obese adults with T2DM when controlling for weight loss between dietary interventions. A systematic review of randomised controlled trials (RCT) was conducted. Electronic searches of Medline, Embase, Cinahl and Web of Science databases were conducted. Inclusion criteria included RCT with minimum 6 months duration, with participants having BMI≥25·0 kg/m2, a diagnosis of T2DM using HbA1c, and no statistically significant difference in mean weight loss at the end point of intervention between dietary arms. Results showed that eleven studies met the inclusion criteria. Only four RCT indicated the benefit of a particular dietary intervention over another in improving HbA1c levels, including the Mediterranean, vegan and low glycaemic index (GI) diets. However the findings from one of the four studies showing a significant benefit are questionable because of failure to control for diabetes medications and poor adherence to the prescribed diets. In conclusion there is currently insufficient evidence to suggest that any particular diet is superior in treating overweight and obese patients with T2DM. Although the Mediterranean, vegan and low-GI diets appear to be promising, further research that controls for weight loss and the effects of diabetes medications in larger samples is needed.
authors.affiliation: 1School of Sport,Exercise and Rehabilitation Sciences,University of Birmingham,Edgbaston,Birmingham B15 2TT,UK.
authors.forename: Amir
authors.initials: A
authors.lastname: Emadian
authors.affiliation: 2School of Clinical Sciences,University of Bristol,Bristol BS10 5NB,UK.
authors.forename: Rob C
authors.initials: RC
authors.lastname: Andrews
authors.affiliation: 3Centre for Exercise,Nutrition and Health Sciences,University of Bristol,Bristol BS8 1TZ,UK.
authors.forename: Clare Y
authors.initials: CY
authors.lastname: England
authors.affiliation: 4School of Psychology,University of Birmingham,Edgbaston,Birmingham B15 2TT,UK.
authors.forename: Victoria
authors.initials: V
authors.lastname: Wallace
authors.affiliation: 1School of Sport,Exercise and Rehabilitation Sciences,University of Birmingham,Edgbaston,Birmingham B15 2TT,UK.
authors.forename: Janice L
authors.initials: JL
authors.lastname: Thompson
mesh_terms: D001786:Blood Glucose / Q000032:analysis*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000178:diet therapy*; D004032:Diet; D038441:Diet, Mediterranean; D000067269:Diet, Vegan; D006442:Glycated Hemoglobin / Q000032:analysis; D038321:Glycemic Index; D006801:Humans; D016239:MEDLINE; D009765:Obesity / Q000150:complications / Q000178:diet therapy*; D050177:Overweight / Q000150:complications / Q000178:diet therapy*; D016032:Randomized Controlled Trials as Topic; D015431:Weight Loss
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin
keywords: ADA American Diabetes Association; Diet; GI glycaemic index; GL glycaemic load; LCM low carbohydrate Mediterranean; Systematic reviews; T2DM type 2 diabetes mellitus; Type 2 diabetes; Weight loss