Eating only 8 hours a day may help control Type 1 diabetes, suggests study

A new UIC study suggests that time-restricted eating could offer a safe and potentially effective way to improve blood sugar control in adults with Type 1 diabetes. The research was led by kinesiology and nutrition professor Krista Varady, a longtime researcher in the field of intermittent fasting.

"This is the first study to examine the effects of intermittent fasting on people with Type 1 diabetes, and the results are extremely promising," said Varady, a leading expert on intermittent fasting who conducted some of the first human studies on the subject.

Testing Intermittent Fasting in Type 1 Diabetes

Type 1 diabetes is a chronic condition in which the body produces little or no insulin, a hormone needed to move glucose from the bloodstream into cells. The condition affects less than 1% of people in the U.S.

For the study, Varady recruited adults with Type 1 diabetes who were also classified as obese according to the Centers for Disease Control and Prevention's body mass index. Varady said this combination applies to about 0.5% of the total U.S. population.

Researchers enrolled 32 participants from the Chicago area and randomly placed them into one of three groups for six months. One group followed a time-restricted eating schedule, consuming food only between noon and 8 p.m. without counting calories. Another group reduced calorie intake by 25%, while the control group made no changes to its usual behavior.

An 8 Hour Eating Window and Blood Sugar

After six months, the time-restricted eating group showed better blood sugar results than the calorie-reduction group. HbA1c, a blood test that reflects average blood sugar over the previous several months, fell by about 0.5% on average in the time-restricted group.

The researchers also found no increase in the risk of dangerously high or low blood sugar levels among participants following the restricted eating schedule. The approach likewise did not raise the risk of diabetic ketoacidosis, which occurs when the body does not have enough insulin and can become life-threatening.

"This is the first step to showing time-restricted eating could be a safe, potentially effective method for people with Type 1 diabetes to manage their blood sugar levels," Varady said.

Researchers Urge Caution

Although the early findings are encouraging, Varady emphasized that the study is only an initial step and should not be taken as a reason for people with Type 1 diabetes to change their eating habits without medical guidance.

"Of course, this is just the first step," she said. "Anyone making changes to their eating habits, especially those with diabetes, must work closely with their endocrinologist or healthcare provider to find a solution that works for them."

Varady next hopes to conduct larger studies across multiple research sites to determine whether the findings hold true in a broader population.

Reference:

Mary-Claire Runchey, Sarah Corapi, Vasiliki Pavlou, Sofia Cienfuegos, Shuhao Lin, Mark Ezpeleta, Kelsey Gabel, Lisa Tussing-Humphreys, Vanessa M. Oddo, Shaina J. Alexandria, Julienne Sanchez, Terry Unterman, Lisa S. Chow, Alaina P. Vidmar, Sirimon Reutrakul, Krista A. Varady. Efficacy and Safety of Time-Restricted Eating in Adults With Type 1 Diabetes: A Randomized Controlled Trial. Diabetes Care, 2026; DOI: 10.2337/dc26-1093