Intermittent Fasting Controls Blood Glucose Levels, Study Finds

August 21, 2018

Patients with T2DM who fasted 2 days a week had weight loss and metabolic outcomes similar to patients who followed a daily kcal-restricted diet.

Type 2 diabetes mellitus (T2DM) patients are just as likely to lose weight and control their blood glucose levels with intermittent semifasting for 2 days per week as with an ongoing daily calorie-restricted diet, according to the first long-term clinical trial comparing the different diets in T2DM.

The results suggest that intermittent fasting could be a solution for people with diabetes who find it difficult to stick to a diet 7 days a week. 

“Conventional weight-loss diets with daily energy restrictions are difficult for people to adhere to so we must look for alternative solutions,” said co-author Peter M. Clifton, MD, PhD, professor of nutrition at the University of South Australia in Adelaide, Australia.

The researchers published their results on July 20, 2018, in JAMA Network Open.

A noninferiority trial randomized 137 patients with T2DM to either intermittent energy restriction (70 patients) or continuous energy restriction (67 patients). The intermittent energy restriction diet of 500 to 600 kcal per day was followed for 2 nonconsecutive days per week, and then the patients followed their usual diet for the other 5 days. The continuous energy restriction diet of 1200 to 1500 kcal per day was followed for 7 days per week. The regimens were followed for 12 months.

An intention-to-treat analysis showed similar reductions in mean hemoglobin A1c (A1c) level between the continuous and intermittent energy restriction groups (–0.5% vs –0.3%), which met the criteria for equivalence. Mean weight change was similar between the continuous and intermittent energy restriction groups (–5.0 kg vs –6.8 kg).

The criteria for equivalence in fat mass or fat-free mass were not met.

Next: Results similar across measures

Results similar across multiple measures

Total weight loss recorded after 12 months was associated with weight change after 2 weeks on the assigned diet. A small number of patients in both groups continued to lose more weight throughout the course of the trial. Similar outcomes were reported for both groups with other clinical markers after 12 months -- improvements in lipid levels, total medication effect score, fasting glucose levels, and total step count.

Similar outcomes were reported for both groups with other clinical markers after 12 months -- improvements in lipid levels, total medication effect score, fasting glucose levels, and total step count.

Hypoglycemic or hyperglycemic events in the first 2 weeks of treatment were similar between the continuous and intermittent energy restriction groups (mean number of events 3.2 vs 4.9), affecting one-third (35%) of the patients using sulfonylureas and/or insulin.

While fasting is safe for people with diet-controlled T2DM, for those using insulin and oral medications likely to cause hypoglycemia, blood glucose levels need to be monitored and medication doses changed accordingly, cautioned the authors.

“Anecdotally, participants in the intermittent energy restriction group reported that although they were not following the protocol consistently after 3 months, they found that they could use it effectively to prevent weight gain because the energy restriction involved only 2 days,” the authors stated.

In conclusion, they stated that “intermittent energy restriction is an effective alternative diet strategy for the reduction of HbA1C level comparable to continuous energy restriction in patients with type 2 diabetes, and it may be superior to continuous energy restriction for weight reduction.”

Source: Carter S, Clifton PM, Keogh JB. Effect of intermittent compared with continuous energy restricted diet on glycemic control in patients with type 2 diabetes: a randomized noninferiority trial. JAMA Network Open. 2018;1(3):e180756. doi:10.1001/jamanetworkopen.2018.0756