A systematic review and meta-analysis of nutrition therapy compared with dietary advice in patients with type 2 diabetes

Background: Despite recommendations, many patients with type 2 diabetes receive dietary advice from nurses or doctors instead of individualized nutrition therapy (INT) that is provided by a dietitian. Objective: We performed a meta-analysis to compare the effect of INT that is provided by a registered dietitian with the effect of dietary advice that is provided by other healthcare professionals. Design: A systematic review was conducted of Cochrane library databases, EMBASE, CINAHL, and MEDLINE in the period 2004-2017 for guidelines, reviews, and randomized controlled trials (RCTs) that assessed the outcomes glycated hemoglobin (HbA1c), weight, body mass index (BMI; in kg/m(2)), and LDL cholesterol. Risk of bias and the quality of evidence were assessed according to the Grading of Recommendations Assessment, Development and Evaluation guidelines. Results: We identified 5 RCTs comprising 912 participants in total. In the first year of intervention (at 6 or 12 mo), nutrition therapy compared with dietary advice was followed by a 0.45% (95% CI: 0.36%, 0.53%) lower mean difference in HbA1c, a 0.55 (95% CI: 0.02, 1.1) lower BMI, a 2.1-kg (95% CI: 1.2-, 2.9-kg) lower weight, and a 0.17-mmol/L (95% CI: 0.11-, 0.23-mmol/L) lower LDL cholesterol. No longer-term data were available. Some of the included studies had a potential bias, and therefore, the quality of the evidence was low or moderate. In addition, it was necessary to pool primary and secondary outcomes. Conclusions: INT that is provided by a dietitian compared with dietary advice that is provided by other health professionals leads to a greater effect on HbA1c, weight, and LDL cholesterol. Because of the potential bias, we recommend considering nutrition therapy that is provided by a dietitian as part of lifestyle intervention in type 2 diabetes, but further randomized studies are warranted.