Fasting may not be part of your daily routine, but it’s something that many people have to do occasionally. For example, Ramadan, the Muslim holiday that continues through this week, involves fasting from before sunrise to after sunset. Certain religious holidays in other religions also require fasting. And before a major surgery involving anesthesia, you’re usually required to fast.

If you have diabetes, fasting involves special planning. That’s because you don’t want to risk lowering your blood sugar too much, which can seriously affect your health. That’s why health professionals who care for people with diabetes often have fasting guidelines for patients. Here are a few steps to consider if you have diabetes and you plan to fast.

[Read: Should You Try Intermittent Fasting?]

Plan with your health care team before you fast. If you have well-controlled diabetes, there’s less of a health risk from fasting. And if you don’t use insulin or a category of diabetes medications called sulfonylureas, then Dr. George Grunberger, an endocrinologist with the Grunberger Diabetes Institute in Bloomfield Hills, Michigan, is less worried about fasting. However, if you have wild blood sugar fluctuations — say, from 400 milligrams per deciliter one day to 50 mg/dL another day — your doctor or certified diabetes educator may advise against fasting. Other people who typically should not fast include pregnant women, those with a history of hypoglycemia (low blood sugar), a history of a diabetes complication called ketoacidosis and sometimes even people working in heavy manual labor, says Amy Kimberlain, a registered dietitian and certified diabetes educator at the Diabetes Research Institute with the University of Miami Miller School of Medicine.

In any case, planning with your health care team can help you approach fasting rationally.

Continue to check your blood sugar while fasting. “Frequent monitoring reduces the risk of both hypoglycemia and hyperglycemia [high blood sugar] and helps control blood sugar levels,” says Dr. Raveendran A.V., an assistant professor of medicine with the Government Medical College in Manjeri, Malappuram, India. A.V. recently wrote a professional article about diabetes control during fasting for Ramadan.

Some people with diabetes may think that checking their blood sugar during fasting hours breaks the fast, but that’s not the case, A.V. says. In fact, Kimberlain recommends checking it more often than usual if you are fasting so you can make sure you stay within a reasonable level. “Regularly monitoring your blood glucose during fasting is key to avoiding health emergencies,” she says. Although low blood sugar is a greater concern while fasting, high blood sugar also can occur.

People who use a continuous glucose monitoring device are able to check their blood sugar more often, leading to less chance of out-of-control numbers.

[Read: 11 Tips for Testing Your Blood Sugar at Home.]

Follow any insulin or medication regimen your doctor recommends for fasting. For instance, Grunberger says some patients who use insulin think they must stop using it during a fast. “That might apply for some patients with Type 2 diabetes, but for Type 1, your life depends on it, and you can’t stop basal insulin,” he says.

Consider making an exception to have small meals. This is something that Sandra Arévalo, a registered dietitian and certified diabetes educator and director of nutrition services for Montefiore Health System’s community programs in Bronx, New York, gently tries to persuade patients to do. Kimberlain has spoken with diabetes patients who fast for religious reasons about not fasting entirely but avoiding foods that bring pleasure and focusing only on foods that keep them sustained and nourished.

Bring a sweet drink (like a juice box) or a small serving of candy with you if you exercise during a fast. That’s because exercise can lower your blood sugar even further, and you want to be ready to help treat that. Although most people with diabetes can exercise normally during fasting, you should avoid overdoing it, especially during the evening hours. That’s when your risk for low blood sugar can rise, A.V. says.

Eat a healthy before-dawn meal if you are fasting for Ramadan. The meal should have some complex carbohydrates and high fiber. Also drink plenty of fluids at that time, A.V. recommends.

Eat a balanced meal after a fast. “Make sure it’s not just carbs,” Arévalo advises. A meal that combines protein, fiber and healthy carbohydrates can help keep your body and blood sugar in balance at any time, but especially after fasting.

[See: How to Make Healthful Dietary Changes Last a Lifetime.]

Know when to break your fast. “A general guideline to break the fast is if a blood glucose of less than 70 mg/dL occurs,” Kimberlain says. This indicates hypoglycemia. “In the case of hypoglycemia, it’s important to break the fast and treat the low with food or drink that contains carbohydrates.” In fact, the risk for hypoglycemia is 4.7 times greater than normal during fasting in those with Type 1 diabetes and 7.5 times greater than normal in those with Type 2 diabetes, A.V. says.

Similarly, Kimberlain believes you should stop fasting if your blood sugar reaches above 300 mg/dL. This would need a correction dose of insulin to stop the blood sugars from escalating further.

Listen to your body. Dark urine, a headache, nausea and vomiting can all be signs of serious dehydration, Kimberlain says. If you experience these signs, you should stop fasting.

Although doctors and other health professionals play a large role in your diabetes care — during fasting or other times — ultimately, your health is in your hands. “The patients are in charge,” Grunberger says.

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9 Guidelines for Fasting When You Have Diabetes originally appeared on usnews.com