Physical activity and daily exercise is crucial for everyone’s health, but even much more so for those with diabetes. Regular workouts not only help lower blood sugar levels, but can improve other health risk factors such as lowering blood pressure and helping with weight control. Research shows that a combination of cardio (aerobic) exercise and weight training is best for overall health.
However, those with Type 1 diabetes, a disorder of the immune system that makes it difficult for the body to produce insulin, run the risk of hypoglycemia (blood sugar that is too low) when working out. To balance the benefits and risks, Canadian researchers say that lifting weights before doing aerobic exercise will control blood sugar better in those with Type 1 diabetes.
Dr. Ronald Sigal, an endocrinologist at the University of Calgary, studied 12 fit people with type 1 diabetes. These volunteers already ran and lifted weights at least three times per week. The average age of the 10 men and 2 women was 32 years old.
The group participated in two experimental exercise sessions, held at least 5 days apart at around 5pm in the afternoon. For the first session, the study volunteers performed 45 minutes of running on a treadmill followed by 45 minutes of weight lifting. For the second session, they reversed the order. Blood sugar levels were measured before, during and after the workouts.
When the participants did the cardiovascular workout first, they experienced a more severe drop in blood sugar levels than when they trained with weights first. “Your muscles utilize sugar very quickly in aerobic exercise," commented Dr. Vivian Fonseca, chief of endocrinology at Tulane University Medical School who was not involved with the study.
What the study couldn’t tell us is if the findings would relate to all people with diabetes, whether Type 1 or Type 2. About five percent of all Americans with diabetes have Type 1, which is often diagnosed in childhood. Most of the remaining 95% have Type 2 diabetes, which occurs over time when body cells stop responding to insulin.
However, those with Type 2 diabetes – and those at risk - should participate in a structured exercise program as inactivity increases the chances of developing diabetes by 14%. A recent study found that Hemoglobin A1c levels (a marker of average blood glucose over a three-month period) was lower when patients participated in at least 150 minutes of a weight training –aerobic exercise program. Diabetics who perform a combination of resistance and aerobic exercises were found in a study to have better overall blood sugar control when compared to inactivity or either type of exercise alone.
For a patient with diabetes, either Type 1 or Type 2, the American Diabetes Association recommends undergoing a detailed medical evaluation. When cleared for exercise, the recommendations are:
- To improve cardiovascular risk, patients should get at least 150 minutes per week of moderate-intensity exercise or 90 min/week of vigorous-intensity exercise, or some combination of the two.
- Patients should exercise on at least three non-consecutive days each week to maximize benefits. Individual sessions should be at least 10 minutes each or longer.
- Resistance training should be encouraged, and should be moderate- to high-intensity — 2–4 sets of 8–10 repetitions at a weight that can’t be lifted more than 8–10 times, with 1–2-minute rest periods between sets.
- Exercise session should include a 5-10 minute warm-up (low-intensity) activity to prepare the skeletal muscles, heart and lung for a progressive increase in intensity. A cool-down activity should be performed at the end of the workout to gradually bring the heart rate to pre-exercise level.
- Avoid exercise is fasting glucose levels are greater than 250 mg/dl, especially if ketosis is present.
- If blood sugar is less than 100 mg/dl, eat a snack that includes carbohydrate. Type 1 diabetics should keep carbohydrate-based foods or a glucose gel nearby during and after exercise.
- Exercise counseling is recommended to assess and adjust levels of physical activity and provide motivation and support.
Jane E. Yardley PhD, Ronald J. Sigal MD MPH et al. Effects of Performing Resistance Exercise Before Versus After Aerobic Exercise on Glycemia in Type 1 Diabetes. Diabetes Care, online February 28, 2012. DOI:10.2337/dc11-1844
The American Diabetes Association, “Diabetes Mellitus and Exercise”, Diabetes Care vol. 25 no. suppl 1 s64, January 2002 doi:10.2337/diacare.25.2007.S64
JDRF (formerly the Juvenile Diabetes Research Foundation)
Harvard School of Public Health, “Simple Steps to Preventing Diabetes”