Exercise is an important tool for managing diabetes as it helps to improve blood sugar levels, increase overall fitness, and reduce body fat. Exercise also reduces the risk of heart disease and stroke. One thing that diabetics should be aware of, however, is that sometimes exercise causes blood sugar to elevate. One of the most important things that all diabetics can do, aside from taking the proper medications, is to monitor blood sugar regularly. Diabetics should test before, during, and after exercise to ensure that blood sugar is at a safe level and to avoid dangerous fluctuations.
Before Exercise
If you take medications to lower your blood sugar, test your blood sugar 30 minutes before and then again immediately before you exercise. If your blood sugar is stable and in the 100 mg/dL to 250 mg/dL (5.6 mmol/L to 13.9 mmol/L) range, you should be safe to exercise. This scenario should not cause blood sugars to increase to an unsafe level after exercise. For those with blood sugar levels above 300 mg/dL (16.7 mmol/L), your levels are likely too high to exercise safely and will likely result in an even higher blood sugar level after exercise.
Exercise and Glucose Levels
In most situations, exercise causes blood glucose levels to drop because the muscles need fuel in the form of glycogen, or glucose, to work. When those glycogen levels get too low, glucose from the blood gets used as fuel for the muscles. After the body stops exercising and the muscles stop requiring glucose to use as fuel, glucose in the blood gets converted into glycogen to replace the depleted cells in the liver and muscles. This causes the blood sugar levels to drop even farther.
Elevated Glucose Levels
In people with high blood sugar levels before exercising, sometimes exercise has the opposite effect. In those whose blood glucose levels are above 250 mg/dL, or 13.9 mmol/L, before exercise, insulin levels are usually too low and exercise should be avoided. Another scenario where blood sugar levels may increase during exercise is when very strenuous exercise causes the liver to release extra sugar into the bloodstream in a response to adrenaline.
Caution
Always consult with your doctor before you start a new exercise program, particularly if you've been inactive recently. Some medications may cause low blood sugar, so make sure your doctor is aware of your exercise routine and says it's safe. Figure out with your doctor what is the best time of day for you to exercise. Generally, it's best to time your workout to between one and three hours after a meal. Never exercise right before bedtime, since you don't want your blood glucose to drop while you sleep and enter into hypoglycemia. Check your blood glucose every 30 minutes during exercise if you work out for longer than one hour.
