How does exercise impact Diabetes?

Diabetes is a disease which the body doesn’t produce enough or any insulin, doesn’t properly use the insulin that is produced, or exhibits a combination of both.  When this occurs, the body is unable to transport sugar from the blood into cells which lead to high blood sugar levels.  Glucose, sugar found in blood, is one of the main energy sources to the body.  A lack of insulin causes sugar to build up in the blood. 

There are two main types of Diabetes: Type 1 and Type 2.  Type 1 diabetes is an autoimmune condition where the immune system attacks the cells inside the pancreas that produce insulin.  Individuals with type 2 diabetes can not use insulin efficiently.  This stimulates the pancreas to continue to produce insulin until it can no longer keep up with the demand.  As insulin production decreases, this leads to high blood sugar. 

Exercise directly impacts blood glucose levels by reducing the levels.  That is because exercise acts like insulin in your body.  Physical activity can lower your blood sugar for up to 24 hours after you workout by making your body more sensitive to insulin. The best way to figure out how your body reacts to a particular exercise is to check your blood sugar level right before and right after working out, especially if you take insulin or are on a medication that causes your pancreas to make more insulin.         

Most individuals think of exercise as running and walking (aerobic exercise), but strength training (such as lifting weights or using a resistance band) plays an equally important role in lowering A1c (amount of red blood cells that have sugar attached). The higher the percentage of A1c, the higher your blood sugar levels have been.  A normal A1c level is below 5.7%. When you exercise, you're teaching your body how to store the sugar in your muscles rather than the bloodstream. The more you exercise, the more your body will effectively use the sugar. Aim for two or three strength-training sessions per week, on nonconsecutive days. If possible, combine those with aerobic exercise to make greater improvements.

People with diabetes should perform aerobic exercise regularly. Aerobic activity bouts should ideally last at least 10 min, with the goal of ∼30 min/day or more, and most days of the week for adults with type 2 diabetes. Dividing aerobic exercise throughout the day, can also help maintain glucose levels.  Daily exercise, or at least not allowing more than 2 days to elapse between exercise sessions, is recommended to decrease insulin resistance, regardless of diabetes type. Over time, activities should progress in intensity, frequency, and/or duration to at least 150 min/week of moderate-intensity exercise.

To prevent hypoglycemia (low blood sugar) during prolonged (≥30 min), predominantly aerobic exercise, additional carbohydrate intake and/or reductions in insulin are typically required.  Blood glucose concentrations should always be checked prior to exercise undertaken by individuals with diabetes.  Individuals should use general guidelines for pre-exercise blood sugar levels.  Lower than 100mg/dL may be too low to exercise safely and may require a small snack of 15-30 grams of carbohydrates to increase glucose levels.  If your blood sugar levels are between 100-250 mg/dL, continue with exercise.  Above 250 mg/dL, this maybe too high to exercise.  If you exercise with too high of blood glucose, you increase the risk of ketoacidosis

Flexibility and balance exercises are likely important for older adults with diabetes. Limited joint mobility is frequently present, stretching increases range of motion around joints and flexibility but does not affect glycemic control. Balance training can reduce falls risk by improving balance and gait, even when peripheral neuropathy is present. This will improve muscle strength prior to potential onset of peripheral neuropathy. Group exercise interventions (resistance and balance training, tai chi classes, and yoga) may reduce falls and helps to provide a support circle for individuals. Physical activity done with peripheral neuropathy necessitates proper foot care to prevent, detect, and prevent problems early to avoid ulceration and amputation. All individuals should inspect the bottoms of their feet prior to exercise and after to assure nothing has gotten in their shoe during exercise to cause a wound.

Physical activity increases bodily heat production and core temperature, leading to greater skin blood flow and sweating. Temperature regulation is only impaired during high-intensity exercise. With increasing age, poor blood glucose control, and neuropathy, skin blood flow and sweating may be impaired in adults with type 1 and type 2 diabetes, increasing the risk of heat-related illness. Chronic hyperglycemia also increases risk through dehydration. Older adults with diabetes or anyone with autonomic neuropathy, cardiovascular complications, or pulmonary disease should avoid exercising outdoors on very hot and/or humid days.

Physical activity and exercise should be recommended to all individuals with diabetes as part of management of glycemic control and overall health. Specific recommendations and precautions will vary by the type of diabetes, age, activity done, and presence of diabetes-related health complications, such as peripheral neuropathy, and should meet the specific needs of each individual. In addition to engaging in regular physical activity, all adults should be encouraged to decrease the total amount of daily sedentary time and to break up sitting time with frequent bouts of activity. Finally, get in the habit of monitoring your blood sugar levels throughout the day, it may one day save your life.