I have type 1 diabetes, and I take Lantus at bedtime with NovoRapid with meals. I have exercised fairly regularly over the years, but have recently become interested (and have become involved with) high level cycling and triathlon and have just begun entering competitions at a veterans’ level. As a result, the level of exercise I have been doing has become much more “focused” with both intensive, high pace sessions (for strength and speed) as well as more steady state recovery and endurance building sessions.

Unfortunately, I have been unable to find advice on managing my diabetes and insulin levels with this intensive type of exercise programme, and my diabetes team has not been very helpful either. Their advice on exercise is more geared towards the general — “just do some walking” exercise advice that’s targeted at the average diabetic population, not intensive levels.

I have read The Diabetic Athlete, but it does not cover my regimen. Specifically, I know that one can skip or reduce the NovoRapid insulin before exercise depending on the blood sugar level prior to exercise provided there is enough insulin in the bloodstream at the time of exercise.

Where can I get good basic advice on the steps I should be taking to manage my diabetes with this type of exercise programme? Is the basal level of insulin that I get from the Lantus adequate in this situation provided my blood sugars are not too high prior to exercise? If I don’t take any NovoRapid prior to exercise and am able to rely on the Lantus in my system, am I “using it up” to an extent that it will not do its proper job later in the day?

As with all types of exercise, I think it is trial and error. You need to start with limited amounts of each exercise to see how it changes your blood sugar and when. You might find that the more intense exercise might even raise your blood sugar though it is more likely to lower it.

If you are doing relatively short stretches of very intense exercise, you may need extra food that works quickly in small frequent amounts. More slowly acting food with protein and fat may start to work too slowly after your blood sugar has already dropped.

If exercise lowers your blood sugar, you may not only have to lower your fast-acting insulin before the exercise, but you may also find you have to lower your Lantus also slightly as frequent exercise may improve insulin sensitivity so that the insulin works a little better, and you need less even when you are not exercising during the night. You can’t “use up” the Lantus during the day so it isn’t available to do its job later. It will work “when it wants to”, and it’s a matter of balancing the food, the exercise, the release of sugar from your liver into the blood, and the insulin working at the time to keep the blood sugar normal.

TGL
Additional comments from Jane Seley, diabetes nurse specialist:

Intensive exercise programs are always tricky! The the only way to know what works for you is trial and error. You are right to cut the NovoRapid and let the background insulin (Lantus) take care of your needs while exercising. Some people find that they need to reduce the Lantus dose as well on exercise days. You will have to experiment with that very carefully.

Additionally, you should contact the Diabetes Exercise and Sports Association (DESA) which has an active group in Europe.

JS