Is intermittent fasting safe and effective for individuals with insulin-treated type 2 diabetes?

This study investigated the safety and effectiveness of intermittent fasting (IF) for 3 non-consecutive days a week, over a period of 12 weeks in people with insulin-treated type 2 diabetes (T2D). The authors concluded that this dietary approach was safe and effective for controlling blood glucose, reducing total daily insulin requirements, and decreasing body weight in participants with T2D.

Dietary modifications often play a role in T2D management. IF involves a switch between times of fasting and eating. IF can include different eating patterns such as limiting food intake to specific times during the day or non-consecutive day fasting. Regardless of the approach, the major goals of IF include overall reduced caloric intake, aid weight loss, and reduced insulin resistance.

Weight gain is often an issue for patients with insulin-treated T2D. Higher insulin doses are needed to control insulin resistance, which may, in turn, result in weight gain and a higher risk of heart disease. There is also a further concern about patients with insulin-treated T2D experiencing low blood glucose during fasting. There is a need to determine the safety and effectiveness of IF in this population.

This study included 46 participants with insulin-treated T2D. They were randomly assigned to an IF treatment group or a control group. 22 participants observed IF for 3 days, weekly. In the IF group, the fasting period was 18 hours. Eating occurred at breakfast and/or lunch with 25% of the recommended caloric intake being allowed during fasting. 24 participants were in the control group, with no fasting restrictions. All participants received insulin glargine (U300) as basal insulin in the morning. At fasting, there was a 20% basal insulin reduction with insulin dose adjustment. Oral non-sulfonylurea medications were allowed during fasting. Changes in HbA1c (glycated hemoglobin; blood glucose control over the past 2-3 months) were measured from the beginning of the study to 12 weeks.

After 12 weeks, a significant reduction in HbA1c levels, body weight, and fat mass occurred in the IF group compared to the control group.

The average total daily insulin dose at the beginning of the study was lower in the IF group (52UI) compared to the control group (59UI). After the study, patients in the IF group had a reduction in total daily insulin dose (45UI), while the control group had an increase in the total daily insulin dose (63UI). There were no episodes of severe low blood glucose.

The study showed improved HbA1c, decreased body weight, and reduced total daily insulin doses after 3 days of non-consecutive IF, weekly, in insulin-treated patients with T2D.

The study design allowed participants to know in each group they were, which may have affected the eating behavior of participants.