A Randomized Pilot Trial of a Moderate Carbohydrate Diet Compared to a Very Low Carbohydrate Diet in Overweight or Obese Individuals with Type 2 Diabetes Mellitus or Prediabetes

PLoS ONE
Q1
Apr 2014
Citations:212
Influential Citations:16
Interventional (Human) Studies
87
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Enhanced Details

Methods
Single-site, parallel-group randomized pilot trial at UCSF, San Francisco, CA. Participants: 34 overweight/obese adults with type 2 diabetes mellitus or prediabetes (HbA1c ≥ 6.0%); age 18+; BMI ≥25. Exclusions included current insulin use, pregnancy, language barriers, or medical/psychiatric conditions that would preclude participation. Randomized 1:1 to MCCR (n=18) or LCK (n=16); 13 sessions over 3 months; not blinded.
Intervention
MCCR: Moderate-carbohydrate, low-fat, calorie-restricted diet with carbohydrate counting: 45-50% of calories from carbohydrate; about 165 g/day; carbohydrate counting using 15 g units; 3 meals and 2 snacks per day; carbohydrate units per meal: 3 and per snack: 1; energy deficit ~500 kcal/day; protein kept constant; fat intake reduced; delivered through 13 weekly 2-hour classes led by a registered dietitian with ADA-aligned guidelines and behavioral-change content. LCK: Very-low-carbohydrate, high-fat, non-calorie-restricted diet aiming to induce nutritional ketosis: net carbohydrate 20-50 g/day; gradual reduction over 7-10 days; ketosis target 0.5-3 mM; no fixed energy limit; protein kept constant; remaining calories from fat; ketosis monitored by home ketone testing (Abbott Precision Xtra) twice weekly to titrate carbohydrate intake; delivered through 13 weekly 2-hour classes with behavioral-change components.
Results
HbA1c decreased by 0.6 percentage points with LCK vs 0.0 in MCCR at 3 months (between-group difference -0.6%; 95% CI -1.1 to -0.03; p=0.04). 44% of LCK participants discontinued at least one diabetes medication vs 11% in MCCR (p=0.03); 31% vs 5% discontinued sulfonylureas (p=0.05). Weight loss tended to be greater with LCK (-5.5 kg) than MCCR (-2.6 kg; p=0.09). All LCK participants who completed 3 months had HbA1c reductions; results suggest that a very-low-carbohydrate diet with behavioral skills may improve glycemic control while reducing diabetes medications in overweight/obese adults with type 2 diabetes or prediabetes over 3 months. Findings are limited by small sample size and short duration and require replication in larger, longer-term trials.
Limitations
Small, single-site, unblinded pilot trial (n=34) over 3 months; includes adults with type 2 diabetes and prediabetes; some baseline differences (e.g., age and sex distribution) and data missing; not generalizable to insulin-treated individuals; short duration with limited follow-up.

Abstract

We compared the effects of two diets on glycated hemoglobin (HbA1c) and other health-related outcomes in overweight or obese adults with type 2 diabetes or prediabetes (HbA1c>6%). We randomized participants to either a medium carbohydrate, low fat, c...