Exercise Safely with Diabetes (Aug , 22, 2022)
Regular exercise is critical for managing blood sugar and general health in diabetes, but there are special safety considerations to understand before beginning an exercise program. The topics discussed in this article are based on the most recent exercise and diabetes guidelines published by the American Diabetes Association (1) and the American College of Sports Medicine (2) as of August 2022, and may need to be updated as the science evolves. These safety steps are summarized in the video below.
Physician clearance. In people with diabetes, there are many situations where a doctor’s clearance for exercise is recommended before the individual starts an exercise program. If you have diabetes, here are some clear situations where a doctor’s clearance is the best approach before you start working out: (A) whether or not you are currently exercising, if you have diabetes and signs and symptoms of cardiovascular (heart and blood vessels), metabolic (diabetes), or renal (kidney) disease (2, 3), if you do not have signs and symptoms and are wanting to do high-intensity exercise like many of The Diabetes Resistance, LLC workout videos, or if you have any diabetes-related complications (examples: retinopathy, peripheral neuropathy, cardiac autonomic neuropathy, or nephropathy) and are wanting to do moderate to high intensity exercise (2). Even if you only want to begin light or moderate intensity exercise like fast walking, being cautious and first obtaining doctor’s clearance could still be helpful. This approach is useful as it opens up a conversation with your doctor about specific exercise-related guidance like physical limitations, possible medication adjustment, meal timing, and target blood sugar levels. While not everyone loves going to the doctor, chances are, your doctor is going to love the fact that you are ready to exercise and want to understand how to do it safely!
Medication adjustment. Exercise is very good at lowering blood sugar, to the degree that care should be taken to make sure that blood sugar levels do not drop too low during or after exercise. Also, some medications that are commonly taken by people with diabetes (examples: diabetes, high blood pressure, and cholesterol medications) may increase exercise risk, and might need to be adjusted (1). If you are taking medication for your diabetes or other other related health complications, asking your doctor if you need to adjust these medications for exercise is the way to go.
Blood sugar levels before exercise. Before each exercise session, it is important for people with diabetes to check their blood sugar levels and make sure that they are between 100-250 mg/dL to safely begin (2). If blood sugar levels are lower than 100mg/dL, eat a carb-rich snack, and then check again to make sure that your blood sugar is between 100-250 mg/dL before starting exercise. If blood sugar levels are above 250 mg/dL, check your urine for ketones. If ketones are found, it is best to delay exercise and discuss this situation with your diabetes doctor. If ketones are not found, it is OK to start exercising, but it is best to be cautious by keeping the exercise intensity levels at mild to moderate (1). For high intensity exercise, wait until your blood glucose levels are below 250 mg/dL. Similar to before-exercise blood sugar levels, a carb-rich snack should be eaten following exercise if after-exercise blood sugar levels are < 100 mg/dL. These high or low blood sugar situations create an opportunity for you to speak with your diabetes doctor about whether or not your insulin dosage or other medications should be adjusted.
Warning signs of low and high blood sugar. It is important to understand the warning signs and symptoms of both low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia) when exercising (2). Some of the signs and symptoms of low blood sugar to watch out for during and after exercise include headaches, weakness, shaking, and heavy sweating. When exercising under normal circumstances, sweating is likely to happen and you may feel weak towards the end of a tough workout, so it is important to be able to distinguish between sweating and weakness caused by exercise versus low blood sugar. This is possible by understanding other symptoms discussed. Other signs and symptoms include hunger, nervousness, confusion, slurred speech, anxiety, tingling sensation in mouth and fingers, changes in vision, mental fatigue, amnesia, seizures, and coma. Some of the signs and symptoms of high blood sugar are similar, while others are unique. They include excessive urination, fatigue/weakness, excessive thirst, breath smelling of acetone (similar to nail polish remover), weight loss for an unknown reason, headache, and difficulty concentrating. Getting in the habit of closely monitoring these signs and symptoms will help you better understand when to stop exercising and possibly refuel with a carb-rich snack.
Exercise timing. The next precaution to take is related to exercise timing. It is best to not exercise at the peak time that blood sugar lowering medication is working, because this may cause blood sugar levels to drop too low (2). It is generally a good idea to avoid exercising right before you go to bed in order to avoid having your blood sugar drop too low while sleeping. When excessive nighttime drops in blood sugar occur, this usually happens within 6-15 hours after exercise, but can occur up to 48 hours after exercise (1). If you have to workout at night, just need to make sure that you are following your doctor’s advice for dietary guidelines, medication adjustments, and exercise. It is important to discuss with a doctor when to exercise and get their recommendation for an appropriate exercise time.
Safety precautions before and during exercise. To prevent low blood sugar during exercise, it is helpful to eat 1-2 hours before exercising, and keep a carb-rich snack like fruit juice in reach during the exercise session in case blood sugar levels get too low (2). Most research has shown that exercising after a meal is a great way to help manage blood sugar (1). It is best for people with diabetes to work with their physician or a registered dietician to help decide any diet changes that may need to be made to safely exercise. Another safety precaution that you can take is to have someone with you or nearby while exercising (2). Next, while a warm-up and cool-down should be a standard part of anyone’s exercise sessions, they are particularly critical components for people with diabetes to avoid cardiovascular (heart) complications. Also related to cardiovascular complications, for those with retinopathy, lighter intensities when performing muscle-strengthening activities may help avoid complications linked to sharp increases in blood pressure (2). Shoes are something else to think about. If you have peripheral neuropathy or peripheral vascular disease, talk to your doctor about appropriate shoes to wear during exercise. Last but not least, maintaining a safe body temperature is another consideration, as many people with diabetes have an increased risk of heat stress during exercise (2). Try to exercise in cool, comfortable temperatures with water on standby to stay hydrated. Drinking water before, during, and after exercise as needed will help you stay hydrated and prevent heat stress. Overheating is a particular concern for older adults and those with autonomic neuropathy (1). I know that this may be a lot to take in, but having this knowledge may increase your confidence in your ability to exercise and lead to healthier routines (4).
Exercise progression. The last topic to discuss is appropriate progression to increase fitness levels in a safe manner for those without complications and who have obtained physician’s clearance for independent exercise. If you are just starting an exercise routine, it is best to begin at moderate intensities, make sure that correct form is being used, and gradually increase the intensity of exercise each week (2). For example, using the Borg’s 6-20 rating of perceived exertion scale (5, 6), it is appropriate for most people to start off at an 11-13 (light to somewhat hard) intensity. Once you are comfortable with the movements and are performing them correctly, including any modified versions of exercises, you can gradually progress up the scale towards 17 (very hard). While many exercises can be learned from watching videos on the internet, the best way to learn proper exercise form is by working with a respected and qualified personal trainer or strength coach.
Exercise can be extremely beneficial for people with diabetes, and taking cautious steps toward exercise may help prevent risky situations from happening. Having a clear line of communication with your doctor about exercise and nutritional requirements, and understanding how to prevent low blood sugar, during and after exercise, can help to increase the benefits while decreasing the risks. Let’s get moving!
Sources used:
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American College of Sports Medicine. ACMS’s Resources for the Personal Trainer, sixth edition. Philadelphia, Wolters Kluwer, 2022.
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