Many people fast for spiritual reasons and for health reasons. Diabetes typically requires that you be careful about supplying your body with adequately spaced meals to stabilize your blood sugar, so fasting must be approached with caution and with the advice of your doctor or dietitian. Still, people with diabetes routinely fast for diagnostic tests, and there's evidence that various forms of fasting may help a diabetic safely control his condition.
At the turn of the 20th century, doctors routinely used fasting practices to literally "starve" diabetes out of patients. Patients would be admitted to a hospital and placed on extreme calorie restriction until doctors could no longer trace "sugar" in the urine. The practice went on for a few years before the discovery of insulin and decades before more evidence-based approaches became mainstream in the nutritional treatment for diabetic patients. Still, the medical profession has come to understand the value of fasting for its many health benefits, some of which apply to diabetics. For example, two cardiorespiratory researchers publishing in the "Nutrition Journal" said fasting has favorable effects on blood pressure, lipids like cholesterol and triglycerides and insulin sensitivity.
Research has examined the effects of both alternate-day fasting and calorie restriction in people with diabetes. In a case of severe calorie restriction, University of Pittsburgh medical researchers demonstrated that a single, seven-period schedule of very low calorie intake produced substantial metabolic improvements for a group of Type 2 diabetics. Participants cycled from a week of 800-calorie days to two months of 400-calorie days back to regular eating before a final weeklong 800-calories-per-day eating plan. The authors of the "Journal of Clinical Endocrinology & Metabolism" report said the first week produced more than 50 percent of the results: improvement of glucose production from the liver and improved insulin secretion and sensitivity. Moreover, people who practice fasting every other day have a lower incidence of diabetes, according to researchers at the University of California, Berkeley.
According to the National Diabetes Information Clearinghouse, more than 80 percent of people with Type 2 diabetes are overweight or obese. Controlling your weight, and losing weight, are important parts of treatment goals for many diabetics. Doing so helps to improve some of the features of the disease and lowers your risk of heart-related complications. The same Berkeley researchers wrote in the "Journal of Lipid Research" that alternate-day fasting works well as a weight-loss aid because it's easier to stick to than extreme calorie restriction on a daily basis. But more than that, in animal research, this kind of fasting also shrinks fat cells and enhances the body's mechanisms for breaking down fats.
Because some diabetes medications, both oral and injections, are taken with meals, you need to be careful with fasting and have your doctor advise you on the safest fasting methods. When fasting for a procedure, certified diabetes educator Nina Watson wrote in "Diabetes Forecast" that you should hold off on oral medication until you are ready to eat again. If you take metformin and your procedure involves an injection, you should hold off on taking the metformin until at least 48 hours after the test. Any insulin that you take with meals should only be taken when you resume eating, Watson reported. Moreover, fasting by some diabetics is associated with serious health consequences like hypoglycemia, diabetic ketoacidosis and dehydration. Pregnant women should not fast.