It is important to think of exercise as one of the most important diabetes medication and you should take it every day. It can work hand in hand very nicely with the other two diabetes management tools – nutrition and pharmaceutical medication. Exercise can help manage diabetes by increasing your cells insulin sensitivity. This will give your pancreas a break. Exercise helps reverse insulin resistance just like nutrition and medication.
With that being said, it is important to take into account a couple things: 1) have you been active or are you just getting started with physical activity and 2) what stage of diabetes you are in (pre-diabetes vs. having diabetes for quite some time). For people who are pre-diabetic, have been somewhat active, and are not on medication at this point in time, a fitness professional can prescribe a more aggressive workout plan for you in terms of the type of exercise, intensity of exercise, and length of time to do the exercise. However, for individuals that have had diabetes for some time, have been mostly sedentary, and are on medication, a trainer would develop a set of lower intensity exercises and recommend doing them for a longer duration. As strength and cardiovascular endurance increase, and blood sugar trends are tracked, the workout prescription will change.
In order to map out these “trends” you, as well as your trainer, need to take into account the type of insulin you are on and how quickly it works in your system (See chart referenced below). This will help you to determine what time of day you should exercise, as well as provide you information on how to manage the blood sugar trends that you will see with exercise.
•Rapid Acting Insulin – Effects start in 10-15min, peak in 1-1.5hrs, and last between 3-4hrs
•Short Acting Insulin – Effect start within 30min, peak in 2-4 hrs, and last between 6-8hrs
•Intermediate Acting Insulin – Effects start in 1-2hrs, peak in 6-8 hrs, and last up to 12hrs
•Long Acting Insulin – Effect start in 1-2hrs with little to no peak, and last ~24hrs
Testing your fasting blood sugar first thing in the morning, as well as before/after exercise will help you to develop the trends and allow you to manipulate insulin/carbohydrate intake at the correct times and in the correct amounts. The goal is to have a target blood sugar level before and after exercise. A reasonable blood sugar target will be specifically individualized for each person. A “before” blood sugar level is typically somewhere between 100-175. An “after” blood sugar level is typically somewhere between 100-140.
Please remember, if your blood sugar is around 90 after exercise, be sure to drink some juice so as the downward trend continues you will be okay to safely drive and go about your day 30-60 minutes after leaving the gym. On the other hand, if your blood sugar is 250 (for Type 1 – check your ketones) or 300 (for Type 2), do a light walk for 5-10 minutes then retest your levels. If it goes down, then there is enough insulin in your blood and you could potentially continue to exercise in a very light capacity. If the blood sugar does not go down, then it is advisable to cancel the exercise session that day and do a supplement re-dose (amount determined by your physician). If you come into the gym and your blood sugar is already in the 250-300 range, keep the intensity low and try some stretching or yoga.
It is a myth that exercise always increases blood sugar. The real fact is that in the presence of adequate insulin – with low to moderate exercise, blood sugar will actually go down! The real reason that blood sugar could potentially increase during exercise would be due to hormones. (Example: adrenaline and the “fight or flight” response). So, this phenomenon would only affect someone who either does not have enough insulin in their blood to begin with or has a resistance to insulin all together. This is the reason the staff at Valley Health Wellness & Fitness Center place such an emphasis on an open line of communication regarding your current health status/medication lists between our staff, you, and your physicians.
Source: MFA Webinar 4/23/13: Diabetes and Exercise, presented by Ryan Bosch BS, ACSM-CES, CDE Exercise Physiologist and Jenna Johnson, MS, ACSM-CES, Exercise Physiologist
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