Diet therapies in patients with type-2 diabetes: A mixed-treatment comparison of randomized control trials

OBJECTIVES: Type 2 Diabetes Mellitus (TTDM) contributes to the body's inability to produce a sufficient amount of insulin in order to sustain glucose levels necessary for energy production. The study aim is to determine the association between multiple diet therapies and the clinical profile of adult patients with TTDM. METHODS: We conducted a mixed-treatment comparison meta-analysis of randomized diet therapies for TTDM patients. Therapies included high carbohydrate and isocaloric (HCI); high carbohydrate and hypocaloric (HCH); low carbohydrate and isocaloric (LCI); and low carbohydrate and hypocaloric (LCH). A systematic literature search was conducted through December 2010. The primary outcomes measured were hemoglobin A1c (HbA1c), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides. These outcomes were dichotomized based upon American Diabetes Association (ADA) standards. A diet was considered successful if the patient's HbA1c was <7%, HDL was =40 mg/dL, LDL was <100 mg/dL, or triglycerides were <150 mg/dL. Mixed-treatment comparison meta-analysis was used to combine direct, within-trial, and betweentrial comparisons with indirect trial evidence from other trials while maintaining randomization. Results are reported as odds ratios (OR) and 95% credible intervals (CI). RESULTS: In total, 10 studies (21 treatment arms and 340 patients) were included in the analysis. For both HbA1c and triglycerides, the HCH diet yielded lower measurements compared to the HCI diet (OR: 0.89 CI: 0.04, 20.86; OR: 0.58 CI: 0.02, 15.55, respectively for HbA1c and triglycerides) and LCI diet (OR: 0.47 CI: 0.02, 7.45; OR: 0.15 CI: 0.001, 6.28, respectively for HbA1c and triglycerides). LDL and HDL cholesterol measurements were not found to be statistically significantly different among the four diet types. CONCLUSIONS: This study illustrated no statistically significant differences existed between the four types of diets with respect to four clinical outcomes. Further research is necessary to identify an optimal diet combination for patients with TTDM.