The effect of medical nutrition therapy by a registered dietitian nutritionist in patients with prediabetes participating in a randomized controlled clinical research trial.

Background: Prior studies have provided evidence that lifestyle change prevents or delays the occurrence of type 2 diabetes mellitus. The challenge is to translate research evidence for type 2 diabetes mellitus prevention into health care settings.

Objective: We investigated the effect of medical nutrition therapy (MNT) compared with usual care on fasting plasma glucose values, glycated hemoglobin (HbA1c), serum lipid levels, and Diabetes Risk Score, from baseline to the end of a 12-week intervention in overweight or obese adults with prediabetes.

Design: Prospective, randomized, parallel group study of 76 adults with impaired fasting plasma glucose or an HbA1c of 5.7% to 6.4%, recruited between April 2010 and May 2011 who completed a 12-week intervention period.

Main Outcome Measures: The primary outcome measure was fasting plasma glucose. Secondary outcome measures were HbA1c, serum lipid levels, and Diabetes Risk Score.

Statistical Analyses: A factorial repeated measures analysis of variance was used to make comparisons between the two groups (the MNT and usual care groups) and two measures of time (baseline and 12 weeks postintervention). Data analysis was performed using the Statistical Package for the Social Sciences (release 19.0, 2010, SPSS Inc).

Results: There was a significant interaction for group assignment and HbA1c (P=0.01), with the MNT group experiencing significantly lower HbA1c levels than the usual care group (5.79% vs 6.01%) after the 12-week intervention. There was a significant interaction for group assignment and Diabetes Risk Score (P=0.001). Diabetes Risk Score for the MNT group decreased from 17.54±3.69 to 15.31±3.79 compared with the usual care group score, which went from 17.23±4.69 to 16.83±4.73. Regardless of group assignment, both groups experienced a reduction in total cholesterol (P=0.01) and low-density lipoprotein cholesterol (P=0.04) level.

Conclusions: The results demonstrate that individualized MNT is effective in decreasing HbA1c level in patients diagnosed with prediabetes.