Twelve-month outcomes of a randomized trial of a moderate-carbohydrate versus very low-carbohydrate diet in overweight adults with type 2 diabetes mellitus or prediabetes

Abstract

Dietary treatment is important in management of type 2 diabetes or prediabetes, but uncertainty exists about the optimal diet. We randomized adults (n = 34) with glycated hemoglobin (HbA1c) > 6.0% and elevated body weight (BMI > 25) to a very low-carbohydrate ketogenic (LCK) diet (n = 16) or a moderate-carbohydrate, calorie-restricted, low-fat (MCCR) diet (n = 18). All participants were encouraged to be physically active, get sufficient sleep, and practice behavioral adherence strategies based on positive affect and mindful eating. At 12 months, participants in the LCK group had greater reductions in HbA1c levels (estimated marginal mean (EMM) at baseline = 6.6%, at 12 mos = 6.1%) than participants in MCCR group (EMM at baseline = 6.9%, at 12 mos = 6.7%), p = .007. Participants in the LCK group lost more weight (EMM at baseline = 99.9 kg, at 12 mos = 92.0 kg) than participants in the MCCR group (EMM at baseline = 97.5 kg, at 12 mos = 95.8 kg), p < .001. The LCK participants experienced larger reductions in diabetes-related medication use; of participants who took sulfonylureas or dipeptidyl peptidase-4 inhibitors at baseline, 6/10 in the LCK group discontinued these medications compared with 0/6 in the MCCR group (p = .005). In a 12-month trial, adults with elevated HbA1c and body weight assigned to an LCK diet had greater reductions in HbA1c, lost more weight, and reduced more medications than those instructed to follow an MCCR diet.

An evidence‐based approach to developing low‐carbohydrate diets for type 2 diabetes management: A systematic review of interventions and methods

“…The high‐protein prescriptions of the included studies ranged from 28% to 65% TEI or 1.2 to 2.0 g/kg IBW per day, and the moderate‐protein prescriptions ranged from 80 to 100 g/d or 0.8 to 1.2 g/kg IBW per day or were equivalent to 20% TEI. One study did not set a quantifiable protein prescription and could not be categorized but encouraged participants to consume their “usual protein intake” …”

“…It appears that no one single CHO amount for T2D is effective, yet there is growing interest in using more pronounced CHO restriction for at least part of the intervention duration. Very‐low‐CHO diet protocols (0‐50 g/d) tended to be described as ketogenic diets and/or set goals to achieve nutritional ketosis as measured by blood ketones . Proposed benefits of nutritional ketosis for T2D include decreased circulating glucose and insulin and increased ketone signalling, which may provide protection against oxidative stress .…”

Improving the scientific rigour of nutritional recommendations for adults with type 2 diabetes: A comprehensive review of the American Diabetes Association guideline‐recommended eating patterns

“…All 27 studies reported outcomes data for people with T2D and thus were appropriate for consideration in the development of nutritional recommendations for T2D management. Of the 10 RCTs, all of which reported on glycaemic control, nine found that a low‐carbohydrate diet resulted in a significant change from baseline to end of study; six also found a superior between‐group reduction favouring the low‐carbohydrate diet . While some studies found that the control diet also improved glycaemic control significantly from baseline, none found the control diet superior to the low‐carbohydrate diet.…”

“…All 12 single‐arm and non‐randomized trials found that a low‐carbohydrate diet significantly improved glycaemic control from baseline to end of study; the two studies that made between‐group comparisons found the low‐carbohydrate diet superior to the control diet . We identified eight longer‐term studies (1‐3 years' duration), of which five found significant glycaemic benefit sustained with a low‐carbohydrate diet; these include two 2‐year trials and a 3‐year trial . Another longer trial also found sustained improvement in glycaemic control at 44 weeks .…”

“…Another longer trial also found sustained improvement in glycaemic control at 44 weeks . All of these studies assessed HbA1c as the primary glycaemic marker, except the study by Dashti et al, which only reported FBG.…”