Ask yourself some questions:
- Do I have a lot of hypos?
- Do my hypo’s happen at a particular time of day or night?
- Do I wake up with a low blood glucose level?
- Do I have a hypo if I miss a meal?
If you answer yes to any of these you need to talk to your diabetes team about the dose, timing and frequency of your background (basal) insulin – for people using injections this means the long-acting insulin such as Lantus or Levemir. For insulin pump users it is the basal insulin infusion rate.
Once this is sorted start planning your exercise
Will my exercise be aerobic, anaerobic or a mixture of both?
Aerobic exercise tends to lower blood glucose levels, anaerobic exercise tends to cause them to rise
When will I exercise in relation to meals?
An injection or bolus (for pump users) of fast-acting insulin (Apidra, Novorapid, Humalog) has its maximal effect on lowering blood glucose levels around 2 hours later. It will make a difference on glucose control when exercise is done in relation to that injection. (see Adjusting Basal Insulin on a Pump or Adjusting Basal Insulin on Injections
How long will I exercise for?
The longer you exercise the more of the bodies stores of glucose will be used up and the greater the risk of a hypo if you do not supplement with extra carbohydrates (see ExCarbs)
Which muscles will I be using?
If you inject insulin into your leg and then start running the insulin can be absorbed more quickly increasing the chance of a hypo. Again the rule is to keep a close eye on your blood glucose levels.
What are my blood glucose levels like before I start to exercise?
Checking blood glucose levels a few times (for example every 30 minutes 2 hours before) before you start to exercise tells you whether they are rising or falling and therefore whether you need to think about extra carbohydrates.
Have I had a significant hypo in the last 24 hours?
A bad hypo at any time increases the risk of having fewer of your usual early warning symptoms of a subsequent low blood glucose level. Best to avoid exercise for the first 24 hours after a severe hypo
Our aim at Excarbs.com is to help people with diabetes using insulin to feel comfortable with taking up exercise – our advice is not aimed at elite athletes but hopefully covers the basic rules for most people living with diabetes.
Remember that if exercise is sustained you will become much more sensitive to the effect of insulin and the dose needed will fall which is a really good result!