Intermittent energy restricted diet results in comparable HbA1c reduction as continuous restricted diet in obese diabetic patients
Effect of Intermittent Compared With Continuous Energy Restricted Diet on Glycemic Control in Patients With Type 2 Diabetes: A Randomized Noninferiority Trial
Introduction and methods
Short periods of severe energy restriction followed by longer periods of habitual eating, or alternate-day modified fasting (intermittent energy restrictions, IER) lead to weight loss equivalent to continuous energy restriction (CER) (3-5 kg within 10 weeks) [1-3], but there are limited data on whether IER has a beneficial impact on glycated hemoglobin (HbA1c) in patients with type 2 diabetes (T2DM).
This randomized non-inferiority trial evaluated the long-term effects of an IER diet compared with a CER diet during a 12-month period in T2DM patients. For this purpose, patients with T2DM, aged ≥18years, and a body mass index (BMI) ≥27 kg/m2 were randomized 1:1 to IER (n=70) or CER (n=67) between 2015 and 2017. The IER consisted of a 500-600 kcal/day diet (including a minimum of 50 g of protein per day) for two days of the week, followed by usual diet for the other five days of the week. The CER consisted of a 1,200-1,500 kcal/day diet (30% protein, 45% carbohydrate, and 25% fat).
Sulfonylureas and insulin were discontinued permanently if HbA1c <7%, or discontinued on IER days only if HbA1c 7-10%, or remained unchanged if HbA1c was >10%. The primary outcome was change in HbA1c level and the secondary outcome was change in body weight. Exploratory outcomes included daily step count, body composition, measured by dual-energy x-ray absorptiometry, fasting glucose and serum lipid levels.
- Out of 137 participants with a mean age of 61.0±9.1 years, mean BMI of 36.0±5.8, and mean HbA1c of 7.3%±1.3%, 70.8% completed the study.
- At 12 months, the mean HbA1c levels were significantly reduced, with no difference between treatment groups (CER: -0.5%±0.2% vs IER: -0.3%±0.1%; P=0.65). The difference between groups of 0.2% (90%CI: -0.2 to 0.5%) confirmed equivalence.
- The mean use of oral hypoglycemic agents decreased significantly by time (P<0.001) and was similar in both groups (P=0.45), but, for insulin, the decrease was significantly greater in the IER group, due to discontinuation on low energy intake days (P=0.006).
- The mean weight reduction was significant over time but not by treatment (CER: –5.0±0.8 kg vs IER: –6.8±0.8 kg; P=0.25). The mean between-group difference in weight change was statistically not equivalent (–1.8 kg; 90% CI, –3.7 to 0.07 kg). Similar results were observed for fat mass.
- The changes in mean fasting glucose and serum lipid levels improved with weight loss (P < 0.001), with no differences between groups. Step count was also similar between groups.
In adult overweight and obese T2DM patients, an IER diet led to equivalent HbA1c reductions compared with a CER diet. An IER diet is acceptable for most T2DM patients and safe for those who do not use hypoglycemic agents. For patients receiving sulfonylureas and/or insulin, regular monitoring of blood glucose levels remains important.