The Truth About Fasting and Type 2 Diabetes

These plans involve going without caloric foods or drinks for an extended period of time—anywhere from 16 hours to several days—and they have become increasingly popular. Research has also found them to be effective for weight loss.

Doctors often advise people with Type 2 diabetes to lose weight, which can have beneficial effects on blood glucose and insulin sensitivity, as well as on the progression of the disease. For this and other reasons, experts are actively looking at the effects of intermittent fasting among people with Type 2 diabetes. However, there are some safety concerns. “People with diabetes should be those who benefit most from intermittent fasting,” says Benjamin Horne, director of cardiovascular and genetic epidemiology at Intermountain Healthcare in Utah. “But these diets also present some of the greatest potential safety issues because of the medications that people with diabetes are typically taking.”

Horne has co-authored several recent papers on the effects of intermittent fasting among people with diabetes. One of them, which appeared in the Journal of the American Medical Association in 2020, looked specifically at the risk profile of these practices. “It’s so easy to start an intermittent fasting regimen on your own, so our main focus was on the safety issues surrounding fasting when you have a diabetes treatment plan already in place,” he says. Based on his and others’ work, Horne says that for most people with Type 2 diabetes—particularly those who are not taking medications to control their blood sugar—the research indicates that intermittent fasting is both safe and likely to be beneficial. However, intermittent fasting isn’t right for everyone. Here, Horne and other experts explain the possible risks of intermittent fasting plans, as well as the benefits and best approaches.

The risks of intermittent fasting 

Low blood sugar, a.k.a. hypoglycemia, can cause a rapid heart rate, sweating, shakiness, and other symptoms. If severe, it can induce weakness, seizures, or even death. People with Type 2 diabetes are at increased risk for hypoglycemia—especially if they go long periods without eating—and this was one of the first dangers experts looked at when assessing the safety of intermittent fasting. “If you are taking medications that are aimed at reducing the amount of glucose in your blood, together with fasting these can cause potentially fatal hypoglycemia,” Horne says. “It’s not a minor safety risk.”