Intermittent Fasting for Diabetics

fasting and diabetes
intermittent fasting for diabetes

Diabetes is a group of diseases that results from the body’s inability to properly remove sugar from the bloodstream. 5% of the U.S. population has type 1 diabetes. Due to genetics or autoimmune disease, type 1 diabetics produce little or no insulin, leaving them unable to regulate the amount of glucose in their bloodstream.   

Type 2 diabetes, sometimes referred to as adult-onset diabetes, begins as pre-diabetes, a condition of chronically elevated blood sugar. The condition is progressive, and eventually, diabetes is diagnosed when the body can no longer produce enough insulin to remove sugar from the blood and transform it into usable energy.

Approximately 84 million Americans are pre-diabetic, and another 30 million have been diagnosed with type 2 diabetes. The common illness can quickly lead to other health problems, including kidney failure, loss of vision and heart disease. 

Preventing and Curing Type 2 Diabetes

Those who are prediabetic can reverse the condition and prevent type 2 diabetes by following a low glycemic diet. Once diagnosed with diabetes, however, doctors are hesitant to say it can be cured, preferring instead to refer to patients with the progressive disease as ‘in remission’ when their blood sugar levels return closer to the norm. 

The treatment for type 2 diabetes entails controlling your blood sugar. This can be done through diet and exercise, and/or medications that induce the body to produce more insulin, become more sensitive to insulin, lower blood sugar, slow digestion or help the kidneys filter glucose from the bloodstream. Type 2 diabetics may also take insulin to boost the amount of insulin working to clear glucose from the bloodstream. 

Recently, scientists have been studying the effects of intermittent fasting (IF) in diabetic patients, as IF has been known to reduce blood sugar, increase insulin sensitivity and boost weight loss, all of which help mitigate diabetes. 

The Science Behind Intermittent Fasting for Diabetes

While there’s work yet to be done, early studies on the effects of intermittent fasting for improving the symptoms of diabetes are promising. 

Recent studies on fasting and diabetes include a 2019 Norwegian study conducted in mice which demonstrated that intermittent fasting specifically reduces pancreatic fat. The study sheds light on how fat cells in the pancreas trigger an overproduction of insulin, resulting in fatigue and eventually, failure to produce insulin at all. 

A comprehensive review of the literature on intermittent fasting for diabetes was conducted in April of 2019. The study provides guidelines for clinicians whose patients are interested in intermittent fasting as a means of diabetes mitigation. We’ve outlined the paper’s pros and cons below. Intermittent fasting for diabetics has both benefits and risks.  

Benefits of Fasting for Diabetes Control

Weight Loss

Those who are diabetic and overweight or obese will benefit from weight loss. Intermittent fasting has been shown effective as a tool for weight loss, potentially with better long term results than caloric restriction alone, as lean muscle mass is retained.  

Weight loss not only decreases pancreatic fat, as mentioned above, but also reduces fat in the liver. Fatty liver disease is frequently co-occurring in patients with diabetes and both conditions exacerbate each other.  

Weight loss is associated with lower hemoglobin A1C rates, and intermittent fasting may improve both body weight and A1C numbers in those with diabetes. The A1C is a measure of your blood glucose levels over the last three months, and is commonly used to diagnose either prediabetes or diabetes.  

Weight loss is also associated with a lower risk of heart disease. The most common cause of death in those with diabetes is heart disease or stroke, as high blood sugar leads to blood vessel damage. A recent study showed intermittent fasting improves markers of heart disease risk. 

Insulin Sensitivity

Intermittent fasting improves Insulin sensitivity in part due to a decrease in visceral fat. However, even in healthy subjects who maintain their body weight, intermittent fasting improves insulin stimulated glucose disposal. 

In 2018, a limited study of just three diabetic patients resulted in all three discontinuing their use of insulin and other medications thanks to intermittent fasting. More studies need to be done with larger and more diverse populations. 

Metabolic Switching

Metabolic switching is a state that arises when the body abstains from food for long enough that it turns from sugar to fat as the primary source of energy. This ketogenic state is induced by intermittent fasting, and is an oft-cited benefit for those who fast for weight loss and fat burning. 

In patients with diabetes, ketosis benefits the liver and pancreas. The liver no longer needs to store excess glucose as glycogen, (glucose is depleted after 12 hours or more with no food) and the pancreas can take a break from the overproduction of insulin. 

Risks of Fasting for Diabetes Control

Those who are new to intermittent fasting, especially if they are coming off a high-glycemic diet, are at risk for feeling the pangs of hunger, fatigue or headaches, as the body adjusts to a new fuel schedule. There are, however, unique risks to intermittent fasting that those with diabetes need to be aware of. 

Hypoglycemia & Hyperglycemia

Hypoglycemia occurs as the result of dangerously low blood sugar levels. You may feel shaky or light-headed, faint or in the worst case, slip into a coma. Hypoglycemia risk increases in diabetics who abstain from food for long periods of time. 

In addition, diabetes medications already put patients at risk for hypoglycemia, which makes combining medication with caloric reduction potentially dangerous. 

A 2018 study on the risk of hypoglycemia due to intermittent fasting in patients with type 2 diabetes found that while participants experienced positive results in weight loss, reduction of A1C levels, fasting glucose levels and improved quality of life, they were, in fact, at a higher risk for hypoglycemia than the control group. The risk remained high despite a reduction in their medications, and regardless of the type of fasting they were doing. 

On the opposite end of the spectrum, hyperglycemia is the dangerous condition of extremely high blood sugar. Those with little insulin sensitivity who break their fast with high glycemic sugary meals are particularly susceptible to this condition. Diabetics should avoid carbohydrate-rich foods during the eating window to prevent this condition.

Disordered Eating

If controlling what or when you eat is an issue, intermittent fasting may not be for you. According to the American Diabetes Association, those with both type 1 and type 2 diabetes are more likely to have experienced disordered eating, and are at higher risk for developing eating disorders.  

intermittent fasting diabetes

For some, going for a long period of time without eating is a trigger to binge when the fasting window is over. This is unhelpful for anyone participating in intermittent fasting but can be particularly dangerous for those with diabetes, as it can trigger the hyperglycemic state mentioned above. 


Keep in mind that you normally get 20% of the water you need from your food. When abstaining from food and sugary drinks for long periods of time, dehydration becomes a risk. Those with diabetes are at increased risk for dehydration because high blood sugar pulls water from the body. If you have diabetes, drink water regularly during the fasting window. 

Can Diabetics Do Intermittent Fasting?

Anyone with pre-diabetes or diabetes should talk to their doctor before beginning an intermittent fasting protocol. This is especially important if your diabetes treatment includes medication. Your doctor will help you understand how to check your blood sugar more frequently, and can recommend adjustments to medications as needed. 

Be mindful of how you feel, and remain aware of the early signs of hypoglycemia, such as lightheadedness. If you do feel hypoglycemic, be willing to break the fasting window if needed — your health must always come first. 

Use caution when exercising or participating in activities that can potentially reduce your blood sugar, and stay hydrated by drinking water regularly throughout the day. 

Doctors recognize the benefit of intermittent fasting for diabetes. These benefits not only arise as a secondary benefit of weight loss, but from the unique changes to metabolic pathways that occur as a result of fasting. 

It won’t be until several more randomized controlled trials are completed that IF will become a standard in diabetes care. Until then, fasting is safe for those with diabetes if done under the supervision of your healthcare provider and with increased glucose monitoring. 

To learn more about fasting benefits please refer to our ultimate guide to intermittent fasting and health.

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