An expert’s guide to exercising and type 1 diabetes

Author: Francesca's story | Posted: 11 October 2016

Francesca Annan BSc(Hons), MSc, RD

Francesca Annan

Clinical Specialist Paediatric and Adolescent Diabetes Dietitian, University College London Hospitals

Managing exercise can be a challenge but it can be done and well managed diabetes is not a barrier to sports performance. There are many successful sports people at all levels with type 1 diabetes.

So what is the secret to success?

It is no secret really, it’s all about monitoring blood glucose (BG) levels and making adjustments to insulin and food (carbohydrate) intake. Managing diabetes during activity is challenging though.

Here are some tips that may help:

Blood glucose monitoring and exercise

The best advice we can give is to check blood glucose levels (BG) more when you are being active. We know it’s actually very easy to miss the signs of a low BG (hypo) during exercise. This is because the actual exercise can feel just like a low whatever your BG. Being distracted whilst you exercise also makes it harder to spot lows.

If you can check twice in the hour before you start then you know if you have a stable, rising or falling BG. Check every 20-30 minutes during the exercise, if you can, then you know what’s happening. Check again when you stop, one to two hours after your activity, before bed and possibly overnight.

Being active may lower your BG during and after the activity. We know that exercise in the afternoon or evening often causes low blood glucose levels between midnight and 4am.exercise

Aim to keep your blood glucose around 6-8mmol/L when you are active /exercising. Below 5.5mmol/L and you are more likely to have a hypo during the exercise and above 14mmol/L you may find your BG just goes up. Sports performance is better when BG is between 6 and 8mmol/L.

Insulin adjustments

If you know when you are going to be active and you know what you will be doing you can plan changes to insulin doses.

If activity is within one to two hours of a bolus/injection of fast acting insulin you can decrease the dose to reduce the risk of lows.

If you know you have a busy, active day ahead you can adjust background/basal insulin.

On a pump you can start a temp basal rate about 60 minutes before you begin an activity and on injected insulin you can lower your morning or night time dose of long acting insulin. Start by dropping the dose by about 20 per cent and then check to see what happens.

Sometimes exercise puts your blood glucose levels up – you will learn through experience how you respond to different types of activity and what adjustments you need to make. Remember that every activity may be a bit different and there are lots of different solutions to managing your BG.

Tips for unplanned activity

Using an insulin pump to treat type 1 diabetes
Insulin pumps deliver insulin via a cannula, but must be told how much to give

When any activity is planned then the monitoring and insulin adjustments can be planned, but life often isn’t like that so here are some tips for unplanned activity:

Check your BG and if you use an insulin pump/smart blood glucose meter check your ‘active insulin’ or insulin on board (IOB).

If you are going to do the types of activity that tend to drop blood glucose levels then here is what to do:

  • If you have had some insulin with food in the last 60-120 minutes there is a bigger chance you may go low during the exercise. Think, do you need some extra carbohydrate before you start?
  • If the pre exercise blood glucose is 8mmol/L or below you are more likely to need extra carbohydrate to prevent a low.
  • If the blood glucose level is 14mmol/L or more do you need to check for ketones? If you know you have eaten in the last 60 -120 minutes and taken some insulin then you should be ok to just monitor, if you have not eaten/taken any insulin in the last 60-120 minutes check for ketones and follow the advice from your diabetes team. A high blood glucose with ketones means you need to eat something before you begin.

Other things to think about include:

  • The weather – hot or cold temperatures can change your usual blood glucose responses – keep a close eye and remember that your blood glucose may go down or up.
  • Doing something new? – when activities are new and unfamiliar you may be more likely to drop your blood glucose level – be prepared.

Top tips for safe activity

  • Always wear/carry Diabetes ID (use medical ID apps on your phone to do this)
  • Always have a blood glucose meter and hypo treatment with you
  • Check blood glucose levels often
  • If blood glucose is below 5-5.5mmol/L or below 8mmol/L and falling have at least 10-15g carbohydrate before you start
  • Drink plenty of fluids
  • If activity lasts longer than 60minutes use a sports drink for carbs and fluids
  • Always eat something containing both carbohydrate and protein after exercise. This may be your next meal or a bedtime snack
  • Always check blood glucose levels before going to bed.

Learn from others

There are many people who manage to exercise successfully with type 1. You can learn from the diabetes online community tips and tricks that may help you.Friends having fun outdoors.

Remember that everyone is different and there is no one way of managing diabetes and exercise that will work for everyone.

If you have any specific questions or concerns please get in touch with your healthcare team.

The views expressed by contributors to the JDRF blog do not necessarily represent the views of JDRF.