Diabetics who exercise

Many people with diabetes are afraid to exercise because they fear low blood sugars (hypoglycemia). But, with careful control and by eating properly, you can succeed in sports. In fact, there are many professional athletes who have diabetes. To be a successful athlete with diabetes, it is going to take some stellar self-management skills. The most important thing that an athlete with diabetes has to worry about is low blood sugars. With proper nutrition and strict control, you too can hit the ball out of the park, or reach the finish line, (all without episodes of hypoglycemia or hyperglycemia).



Diabetes is a metabolic disorder and it affects carbohydrate availability and utilization in the body. Since carbohydrates are one of the main sources of energy for the body particularly during exercise, diabetes severely alters energy metabolism in the body. It occurs when the pancreas does not produce any or enough insulin or the body cannot process the insulin produced. Insulin is a hormone that is the key that unlocks cells allowing glucose to enter. Hence, controlling blood glucose levels in the body.

Type 1 diabetics are reliant on insulin injections to provide what their pancreas fails to produce. It is insulin’s role to transport glucose from the blood into the cell to be used for energy production and glycogen synthesis. Further, insulin prevents glucagon from breaking glycogen to release glucose for energy. These are all normal processes in the non-diabetic that are hindered in the diabetic due to the absence of insulin. Interestingly during exercise contracting muscles can absorb some glucose without insulin and after exercise muscle shows an improved sensitivity to insulin. These are important factors to consider in terms of insulin dosages required before and after exercise and also a valuable point for type 2 diabetics to consider as a beneficial element of exercise in the management of their







In a diabetic, there can be:

  • Excessive insulin availability during exercise
  • Inadequate glucose production by the liver
  • Decreased blood glucose levels
  • Increased glucose uptake by the exercising muscles.

To maintain a healthy glucose and exercise all together it is important to take some factors into consideration.

  • Must balance intake of carbohydrates with daily doses of insulin to prevent hypo/hyperglycemia. The table below shows some signs and symptoms of both.

  • The main objective is good blood glucose control on a daily basis. We are looking to maintain a controlled diabetes with a fasting BG of 70-100 ml/dl daily
  • Must correctly time food intake and insulin administration relative to exercise
  • High blood sugars during exercise are not good. You will want to postpone your exercise plans if your blood sugar is over 300 mg/dl. If your blood sugar is 240 mg/dl or above, you will want to check for ketones with a urine ketone strip before you exercise. These can be purchased at any pharmacy.

If ketones are present, then do not exercise until blood sugars are down below 240 mg/dl, and ketones are absent. The reason that you not exercise when you have ketones present is because kentones signal that there is a need for and lack of insulin. Exercising when ketones are present will burn fat and cause your body to produce more ketones. This can lead to a dangerous condition known as Diabetic Ketoacidosis (DKA).

  • Do not forget to drink plenty of water to avoid dehydration when your blood sugars are high and during your exercise routine in general. Also, dose insulin as it is prescribed to you by your doctor. Do not exercise until you are ketone negative.



  • Aim for Carbohydrates – 45 – 65%, Protein – 15 – 20% and Fat – 20- 30% of total calorie intake.
  • Eat at the same times everyday
  • Eat a similar amount of food in each meal/snack. This will ensure there are no drastic fluctuations in carbohydrate intake
  • It is important to know the amount of carbohydrate in a meal/snack. In this case the type of carbohydrate is not as important as amount consumed.
  • In exercise lasting longer than 30 minutes, type 1 diabetic athletes should consume 15 to 30g of carbohydrate every 30 to 60 minutes.
  • If you are getting ready for some intense training as an athlete with diabetes, you will need to check your blood sugars before you set out on your training excursion. You will not want to start exercising until your blood sugar is greater than 70 mg/dl. If it is not at least 70 mg/dl, you will then need to eat an extra snack prior to your exercise routine.
  • During exercise, your stores of glycogen get depleted. Don’t forget that a low blood sugar could happen anytime, even 4 to a whopping 48 hours after you exercise. You will want to check your blood sugars more often during this time, and make sure to eat regular meals and snacks without skipping any
  • In general, 15 grams of carbohydrates is enough to snackon if you are exercising for 30-45 minutes. However, you should always carry extra snacks with quick-acting carbohydrates in case you need it for a low blood sugar.
  • Eating a high carbohydrate meal the night before a race is recommended for athletes to increase their supply of glucose prior to an event. You should cover the carbohydrates with the right amount of insulin. Your body will store some for the event.
  • Eating 6 small, frequent meals throughout the day that contain carbohydrates, protein, and good fats, is important. This will help to keep your blood sugars steady during events that last the whole day. However, it may be best to avoid high sugar foods and foods with high fat content just before exercise. 
  • After exercising, you need to refuel. Eat a good meal containing all food groups closely following completion of the sporting event.
  • In addition to eating a nutritious meal to avoid post-exercise low blood sugar, you will want to continue to check your blood sugars often. Plenty of water is needed before, during, and after a sporting event. Getting dehydrated can make your blood sugars rise.
  • Ideally, you should start exercising with your blood sugar a little bit higher than you might normally want it to be. Around 160-180 mg/dlis fine for starting a sporting event. Your blood sugar will go lower when you start to exercise as you expend energy.



An athlete with diabetes should have an advanced understanding of how nutrition, insulin levels, and exercise affect them. It is quite the balancing act that they must perform. They have to balance between getting the right amount of insulin and the right amount of carbohydrates in order not to bottom out during a sporting event. The timing of insulin dosing is key to a successful sporting event without incident related to diabetes. Always consult with your primary care provider and dietitian when planning sporting events, and before making any changes in your diabetes plan. You may need adjustments to your medications, diet, or other treatments. We hope this article will help you as you climb to the top of your sport as an athlete with diabetes.



  1. Management of competitive athletes with diabetes. American diabetes Association.
  2. Nutritional concerns in the diabetic athlete. Current Sport Medicine Reports.




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