Exercise snacks are food and drink used to provide fuel for the active muscles and for glucose management (hypoglycaemia prevention and treatment). They may be needed before, during and after exercise and can be important for sports performance.
The snacks you chose will depend on the reason you need them, the type of activity you are doing and how long you are exercising for as well as how you manage your diabetes. The understanding exercise information explains more about how different exercise may impact your glucose levels.
Snack types
Carbohydrate snacks – these snacks provide mostly carbohydrates and are medium or high GI snacks that can be used to raise glucose levels during exercise.
Carbohydrate and protein snacks – these help provide fuel for exercise and protein for muscle repair. They are usually used before and after exercise.
Before exercise
Snacks before exercise are usually taken to provide fuel for exercising muscles or to help prevent low glucose levels during exercise.
Pre exercise snacks for glucose management should be used based on your glucose levels and trend, insulin on board and exercise type. These snacks should be high GI or fast acting carbohydrate. The amount of snack needed will vary with the diabetes management.
Pre workout/training snacks 60 - 90 minutes before exercise, these snacks are taken to top up muscle stores of glycogen and support muscle growth and repair, if a meal is not eaten 2 - 3 hours before exercise. Snacks should include carbohydrates, protein, minimal fat, and provide vitamins and minerals to support a healthy diet. Food 1 - 2 hours before exercise will need some insulin.
Pre workout/training snacks 15 - 30 minutes before exercise, these snacks are usually taken to top up glucose levels before a session. The amount you need will depend on diabetes management, glucose levels, glucose trend, insulin on board and exercise type and duration. These snacks should be faster acting carbohydrate and usually will not require insulin.
During exercise
Snacks for energy (fuel)
For sports and activities that last for longer than 60 minutes you may need to take on board some snacks for energy. These snacks should contain carbohydrate and need to be suitable for the activity you are doing.
For longer duration activity, for example an all-day bike ride or long hike having a mixture of carbohydrate and protein can help to fuel muscles.
For activities that last between 60 minutes and 2 hours carbohydrate only snacks will be fine.
For shorter activities snacks may only be needed for hypoglycaemia prevention or treatment.
How much of a snack do you need?
Use the information below to decide how much of a snack you need before, during and after exercise.
Snacks for hypo prevention
Multiple daily injections or manual pump therapy
Use the table below as a starting guide to how much carbohydrate to have at the beginning and during exercise based on your glucose levels and sensor arrow.
| Exercise within 2 hours of insulin injection or bolus | ||
|---|---|---|
| If glucose level is 7mmol/l or below consume exercise snacks before activity. | ||
|
10 - 15g carb per hour |
15g - 20g carb per hour |
20 - 30g carb per hour |
| Check every 20 - 30 minute and repeat carbohydrate snacks as needed. If your glucose falls you need more, if your glucose levels rise you need less carbohydrate. | ||
Hybrid closed loop system
If you are snacking for hypo prevention and using a hybrid closed loop (HCL) system, aim to keep your glucose levels at the same target as the system uses. This is usually around 8mmol/L.
| Exercise within 2 hours of insulin bonus | ||
|---|---|---|
| If glucose level is 7mmol/l or below consume exercise snacks before activity. | ||
|
3 - 6g carb per hour |
6g - 12g carb per hour |
12 - 20g carb per hour |
| Check every 20- 30 minute and repeat carbohydrate snacks as needed. If your glucose falls you need more, if your glucose levels rise you need less carbohydrate. | ||
Snack size guide
Remember for any activity that usually raises glucose levels you may need to adjust your insulin to prevent high levels if you need snacks for fuel.
| 10-15g carbohydrate snack portions | |
|---|---|
| Banana (115g weighed with skin) | Small box dried fruit e.g. raisins, sultanas, dried pineapple or mango |
| 120 - 140g Fruit e.g. Apple or Orange or Pear | 200 - 250ml isotonic sports drink |
| 30 - 40 ml sports gel | Small cereal bar (check the label) |
| 1-2 Jaffa cakes | 150ml pure fruit juice (mix with 150ml water to make the equivalent of a sports drink) |
After exercise
You may need to have snacks after an activity if
- it is a long time until your next meal
- you are exercising just before bedtime
- you have low glucose levels following activity.
After exercise snacks should contain carbohydrates, protein, vitamins and minerals and be low in fat as part of a healthy diet. Always have something to eat before sleep after exercise in the evening. Snacks eaten after exercise may need a reduced amount of insulin. If you are on injected insulin or manual pump therapy reduce your insulin by 50% with any post exercise snacks. If you are using a hybrid closed loop system you may need to reduce your insulin or use a higher glucose target if you usually experience low glucose levels after exercise.
Remember
Exercise snacks should only be used if you need them to fuel performance or to prevent hypos. You will find that some activities may not need any extra carbohydrate at all. Be guided by your glucose levels.
If you are doing 2 hours or more exercise or training 4 or more times a week then you will also need to think about fuelling your exercise. If you need advice about food and sports performance, contact the team to request an appointment with the dietitians. We have 2 clinics run by dietitians with sports and exercise nutrition qualifications. One clinic is for patients who come to UCLH diabetes clinic and a monthly clinic for referrals. More information about the exercise and diabetes clinics is available on our Children and young people's diabetes page.
Page last updated: 02 September 2025
Review due: 01 September 2027