Dietitians and scientists had previously thought of intermittent fasting as a negative practice, so there isn’t a wealth of high-quality clinical research on how it may affect people with diabetes, says Jason Fung, MD, a nephrologist in Toronto and coauthor of The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting. But attitudes have begun to change, and some newer studies suggest the approach may have benefits, including for people with diabetes. For example, one study found that intermittent fasting lowered insulin resistance in 13 adults with type 2 diabetes. Insulin is a hormone that helps shuttle glucose (sugar) out of the bloodstream; people with type 2 diabetes are resistant to insulin, which results in higher blood sugar levels. In addition, a review of research included several studies that found intermittent fasting reduced fasting glucose levels, weight, and post-meal blood sugar levels in people with type 2 diabetes.

Even with these studies, though, further research needs to be conducted to see whether intermittent fasting is truly safe for people with type 2 diabetes as a whole, experts say. On the other hand, some experts say that intermittent fasting carries risks, especially for people who need to keep their blood sugar levels stable. For starters, skipping whole meals can result in poorer blood glucose control, not to mention issues such as fatigue and reduced energy - and, thus, an increased risk of injury. Skipping meals may also cause people to make poor diet choices, which can have the opposite effect on their waistline and blood sugar. If you haven’t eaten for hours, you may be more inclined to reach for a carb-heavy pastry or plate of pasta, for instance. "Blood sugar management can be a real concern with intermittent fasting for people with type 2 diabetes," Sheth says. "That’s why it’s important to discuss intermittent fasting with your physician, monitor your Glyco Care blood sugar supplement sugar closely, and know that your medications may need to be adjusted as well." Your dietitian or a certified diabetes educator can help guide and support you through this process," she says.

A plan that severely restricts a person’s calories or asks them to skip meals can be hard to stick with long term, too, says Ruth S. Pupo, CDCES, who practices at Adventist Health White Memorial in Los Angeles. Another risk of intermittent fasting for people with diabetes is hypoglycemia, or low blood sugar. One study found that intermittent fasting doubles the risk for hypoglycemia in people with type 2 diabetes. People who are on specific diabetes medications - sulfonylureas, meglitinides, and insulin, in particular - may be at increased risk of this complication, which can be life threatening. People who take these medications may not be candidates for an intermittent fasting diet or will need to adjust their treatment regimens after consulting their physicians before starting one. Certain people, such as those who are pregnant or breastfeeding or have an underlying disease or medical condition, should also avoid intermittent fasting, Pupo says.

"Anytime you have a higher demand for more nutrition, you don’t want to do a fast," she says, explaining that people who are pregnant or breastfeeding require extra calories for themselves and their babies, and fasting can cause them to run out of glucose metabolism support and burn fat, tissue, and muscle. What’s more, if a pregnant person overproduces ketones (a compound that is produced when the body uses fat for fuel), the effect can be harmful to the fetus. Intermittent fasting may also not be safe for elderly people with type 2 diabetes who have a reduced ability to endure hunger. Some people with diabetes also run the risk of developing diabetic ketoacidosis, or DKA, which occurs when your body doesn’t have enough insulin to move blood sugar into your cells for use as energy, according to the Centers for Disease Control and Prevention (CDC). When that happens, your liver responds by producing too many ketones, which can build up in the body and damage the kidneys as well as cause brain swelling, Pupo says.