Type 2 diabetes and fasting: What you need to know

MScrappy diets don’t live up to the hype, let alone serious scientific scrutiny. But intermittent fasting seems to be an exception. These plans involve not eating high-calorie foods or drinks for an extended period of time — anywhere from 16 hours to several days — and they are becoming increasingly common. Research has also found it to be effective for weight loss.

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

Horne is the co-author of several recent research papers on the effects of intermittent fasting in patients with diabetes. One of them who appeared in Journal of the American Medical Association In 2020, the risk profile of these practices was specifically considered. “It’s very easy to start an intermittent fasting regimen on your own, so our primary focus has been on the safety issues surrounding fasting when you already have a diabetes treatment plan in place,” he says. Based on his own work and that of others, Horn says that for most people with type 2 diabetes — especially those who aren’t taking medications to control blood sugar — the research indicates that intermittent fasting is safe and likely to be beneficial. However, intermittent fasting is not suitable for everyone. Here, Horn and other experts explain the potential risks of intermittent fasting plans, as well as the benefits and best methods.

Intermittent fasting risks

Low blood sugar, also known as hypoglycemia, can lead to an accelerated heart rate, sweating, shivering, and other symptoms. If severe, it can cause weakness, seizures, or even death. People with type 2 diabetes are at an increased risk of developing hypoglycemia — especially if they go long periods without eating — and this was one of the first risks experts looked at when evaluating the safety of intermittent fasting. “If you are taking medications that aim to reduce the amount of glucose in your blood, fasting can lead to potentially fatal hypoglycemia,” Horn says. “It’s not a small safety risk.”

For a 2018 study in the magazine diabetes medicine, Researchers in New Zealand found that the incidence of hypoglycemia was increased among people with type 2 diabetes who tried intermittent fasting. However, this increase was in line with the results of other weight loss diets, including traditional methods that encourage people to consume fewer calories on a daily basis. Also, the people in the study were all taking medications designed to reduce blood glucose. “It was the medications, not diet per se, that caused the hypoglycemia,” says study author Brian-Corley, a diabetes specialist with the Capital & Coast District Health Board in New Zealand. Corley says that people who take these medications can reduce their risk of dangerously low blood sugar by working closely with their doctor, monitoring their blood sugar more carefully on fasting days, and educating themselves about how to manage a hypoglycemic episode. . In other words, intermittent fasting plans are not necessarily off the table for these patients; They just need more care. Meanwhile, his study also found that intermittent fasting helped with weight loss and improved measures of fasting blood sugar, hemoglobin A1C and overall quality of life.

For people not on medication to lower blood sugar, Horn says the risk of developing hypoglycemia appears to be very low. “People should still consult with someone who treats diabetes — a doctor like an endocrinologist, or at least a dietitian trained in diabetes treatment,” he says. Like Corley, he says that even people on blood sugar medications can try intermittent fasting as long as they work with an expert. “They shouldn’t or shouldn’t do it often. It’s more about the degree to which they should be monitored.” (This does not include people with type 1 diabetes; Horn says intermittent fasting for this group is risky.)

Aside from hypoglycemia, the second major concern is dehydration. High blood glucose causes a general dehydration of the body, and people with type 2 diabetes are already at an elevated risk. Intermittent fasting may increase this risk if people drink or eat less than usual. (It turns out that food can provide a third or more of the water people consume each day.)

“With dehydration, people with diabetes can have a variety of negative outcomes,” Horn says. Stroke, migraine, and kidney damage are potential problems, especially if the person with diabetes has other health conditions associated with these risks. “So if someone already has a kidney problem — and often diabetics have some kind of kidney problem, if not complete kidney disease — dehydration can do damage,” he explains. While drinking water or other fluids that contain no calories while fasting can reduce this risk, people with type 2 diabetes along with other chronic diseases — such as heart disease or kidney disease — probably shouldn’t try to fast. . The same is true for the elderly and frail people with diabetes. He says: “Fasting stresses the body and the organs.” If you’re weak or sick, not eating is probably a bad idea.

There are a few potential health problems associated with intermittent fasting. However, these are not specific to people with type 2 diabetes. For example, nutrient deficiencies, inadequate protein intake (especially if you are older), and other forms of malnutrition can occur if you are fasting. Also, the safety profile of intermittent fasting has not been well established among pregnant or breastfeeding women, or in young children—all groups with important dietary requirements that differ from those of the general population. Experts say these groups should not fast until the risks and benefits are better understood.

While hidden risks may appear, intermittent fasting – with expert supervision – appears to be safe for most people with type 2 diabetes.

Read more: How can people with type 2 diabetes reduce their risk of health problems

Intermittent fasting benefits

While intermittent fasting may present risks for some, it may also provide benefits that outweigh other approaches. 2017 study in World Diabetes Journal It found that just two weeks of intermittent fasting resulted in significant weight loss (more than 3 pounds on average) as well as improvements in glucose levels. “It is possible that intermittent fasting leads to a decrease in insulin resistance,” says Keri Mansell, co-author of that study and a professor in the School of Pharmacy and Nutrition at the University of Saskatchewan in Canada.

Research supports this hypothesis. Some work in people with diabetes has found that intermittent fasting may increase insulin sensitivity and also reduce blood insulin levels. This is a big deal. “Fasting is basically what we prescribe diabetes medications to do, which is to improve insulin sensitivity,” Horn says. At least one small trial (only for three people) found that following an intermittent fasting diet allowed people with diabetes to stop taking insulin medications completely. The results of this study still need to be replicated in a larger group. However, these types of results are encouraging. Insulin resistance is associated with higher levels of inflammation and other risk factors for cardiovascular disease. “Even when people don’t lose weight on the fasting regimen, some research has found that insulin sensitivity improves significantly,” Horn says. “This is something you don’t usually see with other calorie-restricted diets.”


How can fasting produce these benefits? There are quite a few theories, and many of them may turn out to be true. One major hypothesis — already supported by strong research — is that fasting initiates a type of cellular cleansing process that removes old or unhealthy cells and allows new cells to thrive. Based on this work, some experts argue that the human body is not designed for the modern food environment and the schedule of eating three meals a day in addition to snacks. They say intermittent fasting may closely resemble the way humans have eaten for most of the history of our species.

More work is needed to sort this out. But the research so far suggests that intermittent fasting may provide unique and meaningful health improvements for people with type 2 diabetes.

What is the best fasting plan?

term intermittent fasting It does not refer to a single, well-defined practice. Several different methods fall under the umbrella of intermittent fasting. The three most common and well-studied types are known as time-restricted eating, alternate-day fasting, and the 5:2 diet.

The first—time-restricted eating—involves squeezing all the calories of the day into a single “feeding window” of six to eight hours. For example, a person following this diet might eat between noon and 6 pm every day, and avoid all foods and drinks that contain calories for another 18 hours of the day. Meanwhile, a person on an alternate fasting diet eats normally one day, but the next day consuming few or no calories. Finally, the 5:2 diet involves eating normally five days a week but fasting the other two days.

There are many variations of each of these plans. At this point, it’s not clear which, if any, of these are optimal for people with type 2 diabetes. “I think time-restricted eating is most common, followed by fasting two days a week,” Horn says. “But for now, I would say there is no single plan that stands out as a better option.” The “right” plan, he adds, is one that the patient will stick to. Even if the more intense fasting programs are the most beneficial, it doesn’t really matter if people can’t stick to them.

Read more: The link between type 2 diabetes and mental disorders

How to start intermittent fasting

The first step is always to talk with your doctor or care team. They should be able to help you weigh the benefits and risks, identify dietary approaches to avoid nutritional deficiencies and, if necessary, adjust any medications you are taking to avoid problems. “Safety has to come first,” Horn says.

However, don’t be surprised if your healthcare provider isn’t enthusiastic about the fasting diet. These plans are still relatively new, and are not generally taught in medical school. “People may encounter opposition, or their physician may not be very familiar with these regimens,” Horn says. If your doctor says fasting isn’t right for you, that’s one thing. But if he seems to ignore fasting in general, it may be worth seeking a second opinion from a provider who has experience with these plans.

Intermittent fasting can be risky for some. But there is now evidence that it may be a beneficial alternative, or even better, to classic weight loss plans for people with type 2 diabetes.

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