Medical Nutrition Therapy and Weight Loss Questions for the Evidence Analysis Library Prevention of Type 2 Diabetes Project: Systematic Reviews

BackgroundEleven recommendations, based on systematic reviews, were developed for the Evidence Analysis Library's prevention of type 2 diabetes project. Two recommendations, medical nutrition therapy (MNT) and weight loss, were rated strong.ObjectivePresent the basis of systematic reviews for MNT and weight loss recommendations.MethodsLiterature searches using Medline were conducted to identify studies that met eligibility criteria. The MNT literature search covered a time span of 1995 to 2012, the weight loss literature search covered 2008 to 2012 due to inclusion of a Cochrane Review meta-analysis of randomized controlled trials (RCTs) published in 2008. Eligibility criteria for inclusion of articles included original research using higher-quality study designs (ie, RCTs, case control, cohort, crossover, and nonrandomized trials) with participants aged >18 years and meeting prediabetes or metabolic syndrome diagnostic criteria. MNT was defined as individualized and delivered by a registered dietitian nutritionist or international equivalent and length of weight loss interventions was ≥3 months.Main outcome measuresTwo-hour postprandial blood glucose level, glycated hemoglobin level, albumin-to-creatinine ratio (metabolic syndrome samples only), fasting blood glucose level, high-density lipoprotein cholesterol level, systolic and diastolic blood pressure, triglyceride levels, urinary albumin excretion rate (metabolic syndrome samples only), waist circumference (WC), and waist-to-hip ratio were evaluated.ResultsFor MNT, 11 publications were included, with all 11 using an RCT study design and 10 including participants with prediabetes. A majority of publications reported significant improvements in glycemic outcomes, WC, and blood pressure. For weight loss, 28 publications were identified, with one meta-analysis (only included RCTs) and 20 publications using an RCT study design, with the meta-analysis and 10 RCTs including participants with prediabetes. A majority of publications reported significant improvements in glycemic outcomes, triglyceride level, WC, and blood pressure.ConclusionsSystematic reviews provided strong evidence that MNT and weight loss alter clinical parameters in ways that should reduce the risk of developing type 2 diabetes.