The three exercise questions to live by:
1. What is my blood glucose?
2. How much insulin do I have circulating?
3. What am I going to do?
Questions 1: What is my blood glucose?
This is an obviously important question. If the BG is too low, exercise cannot be started, and if the BG is too high, exercise cannot be started. The following are recommendations from Riddell, MC, et al. Lancet Diabetes Endocrinol. 2017; 5:377-90 and are good general guidelines for starting exercise.
BG <90mg/dl
-Consume 10-20g of glucose and delay exercise until BG>90mg/dl.
· BG 90-125mg/dl
-Consume 5-10g of glucose
-Anaerobic exercise can be started
BG 126-270mg/dl
-Aerobic exercise can be started
-Anaerobic exercise can be started, but if you are on the higher end of this range, keep in mind that glucose may rise. Consider giving partial correction. I usually give 50% recommended dose.
BG >270mg/dl
- Check ketones
-I would recommend delaying exercise
Glucose intake for all the above scenarios will need to be higher if there are high levels of insulin circulating.
That brings us to the next question. How much insulin do I have circulating?
I typically recommend going into exercise with as little bolus on board as possible. Most of us have a workout schedule which makes this a lot easier. I, for instance, always do a boot camp class at 5pm. I, therefore, do not eat anything requiring a bolus after 2pm. This helps me go into my workout with very little bolus on board preventing hypoglycemia during my workout. A big bolus right before a workout WILL CAUSE hypoglycemia. This is simple physiology. The glucose that you bloused for is used up quickly during exercise while high amounts of insulin continue to circulate and continue to lower the blood glucose levels.
What am I going to do?
As most of us know, aerobic exercise tends to drive the BG down, while anaerobic and high intensity interval training tends to drive the blood glucose levels up.
Examples of aerobic activity include; running, swimming, hiking, spinning, biking, and dancing. These exercises increase insulin sensitivity and glucose uptake by muscle cells. At the same time, the body fails to reduce circulating insulin levels (because helloooo, our pancreas doesn’t work) limiting glucose production by the liver all leading to hypoglycemia.
Examples of anaerobic activity include weightlifting, sprints, jumping, and push-ups. Anaerobic exercise increases catecholamines, increasing insulin sensitivity. When the pancreas fails to increase insulin levels, glucose production by the liver increases and skeletal muscle glucose uptake is limited. This all leads to hyperglycemia.
My exercise rules:
1. Begin exercise between 120-250mg/dl
2. Go into exercise with as little bolus on board as possible. Keep in mind, some insulin is still needed to bring glucose into the cells. Basal insulin should suffice in most cases.
3. Anaerobic before aerobic
4. Always carry glucose
This quarantine is a GREAT time to establish an exercise routine and work on your work-out goals. We may as well try to find some good in this horrible situation. Am I right?
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