OBJECTIVE To compare the clinical effects of a Personalized Postprandial-Targeting (PPT) diet vs a Mediterranean (MED) diet, on glycemic control and metabolic health in prediabetes.

RESEARCH DESIGN AND METHODS We randomly assigned adults with prediabetes (n=225) to follow a MED diet or a PPT diet for a 6-month dietary intervention and additional 6-month follow-up. The PPT diet relies on a machine-learning algorithm that integrates clinical and microbiome features to predict personal postprandial-glucose-responses (PPGR). During the intervention, all participants were connected to continuous glucose monitoring (CGM) and self-reported dietary intake using a smartphone application.

RESULTS Among 225 participants randomized (58.7% women; mean±SD age, 50±7 years; BMI, 31.3±5.8 kg/m²; HbA1c, 5.9±0.2% (41±2.4 mmol/mol); fasting plasma glucose 114±12mg/dl [6.33±0.67 mmol/L]), 200 (89%) completed the 6-month intervention. A total of 177 participants additionally contributed 12-month follow-up data. Both interventions reduced the daily time with glucose levels above 140 mg/dl (7.8 mmol/L) and HbA1c levels, but reductions were significantly greater in PPT compared to MED. The mean 6-month change in ‘time above 140 mg/dl (7.8 mmol/L)’ was -0.3±0.8 hour/day and -1.3±1.5 hour/day for MED and PPT, respectively (95% CI between-group difference, -1.29 to -0.66; p<0.001). The mean 6-month change in HbA1c was -0.08±0.19% (-0.9±2.1 mmol/mol) and -0.16±0.24% (-1.7±2.6 mmol/mol) for MED and PPT, respectively (95% CI between-group difference, -0.14 to -0.02; p=0.007). The significant between-group differences maintained at 12-month follow-up. No significant differences were noted between the groups in an oral glucose tolerance test (OGTT, CGM-measured).

CONCLUSIONS In this clinical trial in prediabetes, a PPT diet improved glycemic control significantly more than a MED diet as measured by daily time of glucose levels above 140 mg/dl (7.8 mmol/L) and HbA1c. These findings may have implications to dietary advice in clinical practice.