A UIC study led by kinesiology and nutrition professor Krista Varady found that time-restricted eating may be a safe, effective tool to control blood sugar in adults with Type 1 diabetes.
“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.
Type 1 diabetes, a chronic condition of low or no insulin production, affects less than 1% of people in the U.S. For the study, Varady recruited people with Type 1 diabetes who are also classified as obese by the Centers for Disease Control and Prevention’s body mass index . This encompasses about 0.5% of the total U.S. population, Varady said.
In the study, 32 participants from around Chicago were randomly assigned to one of three behaviors for six months: time-restricted eating (eating only between noon and 8 p.m.) with no calorie counting, maintaining a 25% calorie reduction or a control group with no change in behavior.
After six months, Varady observed that the time-restricted group had reduced their blood sugar levels compared to the calorie-counting group; the HbA1c blood test showed an average decrease of about 0.5%.
Importantly, time-restricted eating did not increase the risk for extreme high or low blood sugar levels or diabetic ketoacidosis — a life-threatening lack of insulin in the body.
“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.
“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.”
Next, Varady hopes to run larger, multisite studies to demonstrate these results on a more universal scale.
Other UIC authors on the study are Mary-Claire Runchey, Sarah Corapi, Vasiliki Pavlou, Sofia Cienfuegos, Shuhao Lin, Mark Ezpeleta, Kelsey Gabel, Lisa Tussing-Humphreys, Vanessa M. Oddo, Julienne Sanchez, Terry Unterman and Sirimon Reutrakul.
Varady is also an affiliate of the University of Illinois Cancer Center .
Written by Jenna Kurtzweil
Diabetes Care
Efficacy and Safety of Time-Restricted Eating in Adults With Type 1 Diabetes: A Randomized Controlled Trial
17-Aug-2026