112-OR: Low Carbohydrate vs. Mediterranean Diets in Adolescents with Type 1 Diabetes—A Randomized Control Trial

Objective: To compare glycemic parameters and metabolic health of a low carbohydrate diet (LCD) versus a Mediterranean diet (MED) in adolescents with type 1 diabetes.

Research Design and Methods: In an open-label, randomized, non-inferiority trial, 40 individuals with type 1 diabetes, aged 12 to 22 years, were randomly assigned (1:1) to LCD (50-80g of carbohydrates per day) or MED for 24 weeks. Glycemic outcomes included time in range (TIR), time below range (TBR) time above range (TAR), and glycosylated hemoglobin (HbA1c).

Results: Baseline characteristics were similar between the two groups. After 6 months intervention, the median (IQR) TIR70-180 mg/dL increased from 47% (35;55) to 58% (51;72) in the LCD and from 52% (38;60) to 67% (50;73) in the MED group (p=0.21, p=0.86, respectively). There was no difference in %TBR<54 mg/dL. The delta %TAR>250 mg/dL was significantly greater in the LCD (-11.0 (-5.0; -16) than the MED group (-3.1 (0.0; -9.4)) (p=0.008). HbA1c level improved in both groups, after correcting for gender, age, diabetes duration, and, maternal education; the delta HbA1c was significantly greater in LCD than MED after 6 months -0.8 (-1.3; -0.3) and -0.1 (-0.8;0.2) respectively (p=0.02). Median daily carbohydrate intake was 60gr (45;88) for the LCD and 128gr (IQR 104;155) for the MED group. Delta BMI Z-score was greater in the LCD -0.1 (-0.3-0.1) than the MED group 0.0 (-0.1-0.1) (p=0.08). Lipid levels did not differ between the groups.

Conclusions: Non-inferiority (13% relative margin) of LCD versus MED was demonstrated on %TIR70-(primary endpoint) among adolescents with type 1 diabetes, with no increased risk for hypoglycemia and no effect on cardiovascular risk factors.