* Part 1 of a three-part guest series on Diabetes & Exercise *
Dr. Matthew Corcoran is a clinical endocrinologist, a CDE, and a self-proclaimed diabetes-exercise freak. He's the founder of Diabetes Training Camp, which was featured in Newsweek a couple of years ago. Today, he shares his expert tips for working out hard without crashing hard. Maybe get out your pencil and prepare to take notes...?
A Guest Post by Matt Corcoran, MD, CDE
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Another work day behind and the sun's still bright. Perfect! You have thought about this run the entire day. You put your shoes on, lace them up, head out the door, and...boom...the meter heads south to 56 in the first twenty minutes. You are quickly reminded of the many factors that increase the risk of hypoglycemia during exercise, highest among them the level of circulating insulin. While there is no equation to eradicate the risk of exercise-induced hypoglycemia, consider your controllables, understand the uncontrollables, and continue to build a foundation for success in between those workouts.
For those who work out at moderate intensities, lower insulin levels often help decrease the risk of exercise-induced hypoglycemia. The long acting basal insulin preparations (Levemir and Lantus) are marketed and sold as 24 hour and non-peaking, but you have probably experienced their heightened activity 4-8 hours out. If you are looking for less insulin on board during your workout you may be better served to adjust the timing of workouts so that they fall at the tail end of a dose. Still, it is challenging to alter the basal levels too much for those that rely on injections, and carbohydrate supplementation will be necessary. If you rely on pump therapy, you may find it more effective to adjust your basal rates 90-120 minutes before jumping on that elliptical to lower those insulin levels. Most will find good success with basal rates between 50-75% of normal.
Regarding pre-workout boluses, there is plenty of advice on how to adjust prior to exercise. If taken within 30-90 minutes of exercise, your bolus may need to be reduced by 50-75%. While this creates more cushion for your glucose to fall, it characteristically results in a post-meal spike that repeated over time may not be the best for long-term vascular health.
The bottom line is that there is nothing complimentary about peaking insulin and a workout. You want to talk about a rapid fall: 120-180 points an hour in some cases. That is moving fast, and, if nothing else very disconcerting. If you truly want to diminish your risk of hypoglycemia during exercise, see if you can practically separate those meal time boluses and your exercise by three to four hours.
Regardless of the strategy, exercise and insulin pack a powerful one-two punch; some carbohydrate supplementation will most likely be required by your working muscles that are churning through carbohydrates rapidly. A solid nutrition plan to fuel your working muscles plays a vital role and an empty tank at the start does not bode well. Eat well and healthfully in-between workouts to refuel that tank!
Next, consider some of the uncontrollables (or, less controllables). Daytime exercise increases the risk of hypoglycemia in the middle of the night when your defense system is blunted. In fact, these lows often go unrecognized. An unrecognized low in the middle of the night actually impairs your body's response to exercise and hypoglycemia the following day. Even if you don't have a low during the night, the previous day's exercise impairs your hormonal response to exercise and defense against lows the following day. If your head is not spinning yet, try to remember this: prevention of hypoglycemia at all times will go a long way to lowering your risk at more specific times, like during your next workout.
Making things most complicated is the fact that there is no equation, no one-size-fits-all strategy that will work for everyone. Diabetes and exercise mandates an individualized plan. But, consider this: most of us mere mortals will only engage in exercise or training 5-10 hours a week. This leaves about 158 other hours for diabetes management and control.
With each opportunity to work with those with diabetes the more I recognize the importance of base, a foundation. Despite all the tailored strategies and approaches to diabetes management for exercise, it is really what happens in between that will most impact your results during exercise. Build your base and control the controllables- take the time to optimize your basal insulin supply, meal time and correctional strategies, and assess your hypoglycemia risk. Take the time and make the effort to bring stability to all of hours that you aren't in the gym, and stability will follow during well planned exercise and training sessions.
Thank you, Matt, for this methodic approach to "pushing the envelope" with the Big D.