Worried about blood sugar? How to eat, before or after exercise?

If your blood sugar level is less than 100 mg/dl, please take a snack containing 15-30 g of carbohydrates. Examples of ready-to-eat carb items could be a small fresh fruit, half a sandwich with unsweetened peanut butter, half a cup of oatmeal, a cup of sugar-free yogurt, whole grain cereals or Greek yogurt and fruit.

If your blood sugar is over 300 mg/dl, it may be too high to exercise safely, especially if you are on insulin. Test your urine for ketones. The body makes ketones when it does not have enough insulin and breaks down fat for energy. Exercising when you have a high level of ketones can be dangerous; it can lead to a condition called ketoacidosis.

Exercise at least an hour after you eat so that your blood sugar level is in the safe zone. When it’s been about three to four hours since you last ate, your body is more able to burn fat for fuel, so it’s even better.

During exercise: Watch out for low blood sugar

During exercise, low blood sugar is a risk for those who take insulin or medication. If you are starting a long workout session, checking sugar every 30 minutes during the activity is ideal although it may be a challenge. The good news is that if you are a well or moderately-controlled individual with Type 2 diabetes and are taking medicines like Metformin, DPP4 inhibitors (sita-, lina- or vildagliptin) or SGLT2 inhibitors (empa-, dapa-, or canagliflozin) no major precautions are required for exercise except adequate hydration. These drugs do not send your blood glucose level plummeting.

An important advancement in this area is the use of continuous glucose monitoring in which a glucose sensor is attached to the body. This records blood glucose continuously and obviates the need for multiple pricks. Increasingly, people with diabetes, especially those on insulin, are opting for these easy to use devices.

If your sugar drops below 70 mg/dl with symptoms —tremors, shakiness, dizziness, confusion or fainting — stop exercising and take 15 g carbohydrates like glucose tablets or powder, three spoons of sugar, candy, a soft drink or fruit juice. Check your blood sugar again 15 minutes later. Repeat till you reach a sugar level of 70mg/dl. It is advisable to avoid exercise for 24 hours if you’ve had a serious low blood sugar reaction requiring assistance.

After exercise: When should you check your blood sugar?

If you are taking insulin or sulphonylureas, check your blood sugar as soon as you finish exercising and ideally every hour for the next 3-4 hours. Exercise utilises sugar stored in your muscle and liver. These stores are replenished by the body after exercise, for which it utilises blood sugar. A drop in blood sugar can, therefore, occur several hours after a long workout (delayed hypoglycaemia).

Having a snack with slower-acting carbohydrates (for example dried fruits, roasted chana, hummus with vegetables, egg and boiled sweet potato salad) can prevent a drop in your blood sugar. If you have low blood sugar after exercise, eat a small snack that has carbohydrates.

Just follow the basics, and enjoy your workout.