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For type 2 diabetes, intermittent vs. continuous energy restriction yields similar glycemic improvements

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July 20, 2018

Peter Clifton
Peter M. Clifton

Adults with type 2 diabetes and obesity randomly assigned to an intermittent fasting intervention or continuous energy restriction experienced similar decreases in HbA1c over 12 months, according to findings published in JAMA Network Open.

“The results demonstrated that a 2-day intermittent energy restriction diet is comparable to a continuous energy restriction diet for improvements in glycemic control, confirming our pilot data,” Peter M. Clifton, MD, PhD, of the School of Pharmacy and Medical Sciences at the University of South Australia, and colleagues wrote. “Equivalence was demonstrated for change in HbA1c level; however, given the large variability in weight reduction, equivalence could not be demonstrated for weight loss or changes in body composition.”

Clifton and colleagues analyzed data from 137 adults with type 2 diabetes (77 women; mean age, 61 years; mean BMI, 36 kg/m²; mean HbA1c, 7.3%) randomly assigned to an intermittent energy restriction diet, consisting of a 500 kcal to 600 kcal per day diet for 2 nonconsecutive days per week with usual diet the remaining 5 days (n = 70) or a continuous energy restriction diet, consisting of a 1,200 kcal to 1,500 kcal per day diet 7 days a week for 12 months (n = 67). Medications likely to cause hypoglycemia were reduced at baseline according to medication management protocol. Primary outcome was change in HbA1c; secondary outcome was weight loss with equivalence set at ± 2.5 kg.

Within the cohort, 97 adults completed the trial. To replicate a real-world environment, no meal replacements or foods were provided, the researchers noted, adding that overall compliance to both diets was high for the first 3 months.

Intention-to-treat analysis showed a similar mean HbA1c reduction between the intermittent and continuous energy restriction groups (mean, –0.5% vs. –0.3%, with a between-group difference of 0.2%), meeting the criteria for equivalence, according to researchers. Researchers observed an increase in mean HbA1c in both groups between 3 and 12 months, with an overall decrease of 0.4% at 12 months (P < .001). In stepwise linear regression analysis, baseline HbA1c accounted for 35% of the variance in the change in HbA1c at 12 months, whereas change in visceral adipose tissue accounted for 17% of the variance in change in HbA1c at 12 months, with no effect of treatment group, the researchers wrote. Those with a baseline HbA1c of more than 8% experienced the greatest mean change in HbA1c over 12 months, whereas those with a baseline HbA1c of less than 6% experienced little to no change in HbA1c.

Mean weight change was also similar between the intermittent and continuous energy restriction groups (mean, –5 kg vs. –6.8 kg); however, the between-group difference did not meet the criteria for equivalence. The between group difference for loss in fat mass also did not meet criteria for equivalence, according to researchers.

At 12 months, researchers observed no between-group differences for step count, fasting plasma glucose level, lipid levels or total medication effect score. There were no between-group differences for episodes of hyperglycemia and hypoglycemia in the first 2 weeks of the intervention, which affected 35% of participants using sulfonylureas and/or insulin, according to researchers.

The researchers noted that the study was limited to patients with well-controlled diabetes, and that medications adjustments for those on insulin or sulfonylurea therapy can interfere with any interpretation of change in HbA1c, although any changes to medications were similar between groups. Additionally, participants had more contact time with a dietitian vs. a typical clinical setting, which may have affected results.

“Intermittent energy restriction is a useful strategy for weight loss in type 2 diabetes and may be superior to continuous energy restriction,” Clifton told Endocrine Today. “However, careful medication management is required to avoid hypoglycemia.” – by Regina Schaffer

Disclosures: The authors report no relevant financial disclosures.


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