Exercise and Diabetes

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November is not only the month where the “turkey madness” begins (with US Thanksgiving and December’s holidays feasts), it’s also National Diabetes Month (in the US and Canada).  According to the International Diabetes Foundation, 371 million people worldwide live with diabetes.  In fact, diabetes affects an estimated 20.8 million Americans (about 6.2 million are undiagnosed and therefore unaware that they have the disease), with an estimated 1.5 million Americans diagnosed each year.  In support of National Diabetes Month (and “World Diabetes Day” on November 14th), TodaysFitnessTrainer.com is dedicating this post to understanding the effects of exercise and diabetes prevention and management.

What is Diabetes?

Diabetes (aka. diabetes mellitus), is a chronic disease that occurs when the pancreas (both an endocrine gland and a digestive organ) is no longer able to make insulin (a hormone important for the metabolism of carbohydrates and fat in the body), or when the body cannot make good use of the insulin it produces.  Made by the pancreas, insulin acts like a key that lets glucose (from carbohydrates we eat) pass from the blood stream into the cells in the body to produce energy. In other words, insulin helps glucose get into cells.

Not being able to produce insulin or use it effectively leads to raised blood glucose levels (known as hyperglycemia), which can lead to damage to the body and organ failure over time.

• Being very thirsty
• Frequent urination
• Weight loss
• Increased hunger
• Blurry vision
• Irritability
• Tingling or numbness in the hands or feet
• Frequent skin, bladder or gum infections
• Wounds that don’t heal
• Extreme unexplained fatigue

There are three (3) main types of diabetes:

1. Type 1 diabetes – is usually caused by an auto-immune reaction where the body’s defense system attacks the cells that produce insulin (also known as “juvenile-onset diabetes).  People with this form of diabetes need insulin injections every day because they produce very little or no insulin (which is essential for survival).
2. Type 2 diabetes – is characterized by insulin resistance and insulin deficiency (and accounts for at least 90 percent of all diabetes cases).  It is often associated with overweight or obesity, which itself can cause insulin resistance and lead to high blood glucose levels.  People with type 2 diabetes may be able to manage their condition through exercise and diet, but over time most will require oral drugs or insulin injections.
3. Gestational diabetes (GDM) – is a form of diabetes that results in high blood glucose levels during pregnancy.  It is associated in complications in both the mother and baby and, although is usually disappears after pregnancy, women with GDM and their children have an increased risk of developing type 2 diabetes within ten years after delivery.

Before people develop type 2 diabetes, they almost always have “prediabetes” (blood glucose levels that are higher than normal but not yet high enough to be diagnosed as diabetes). Prediabetes is also known as either impaired glucose tolerance (IGT) or impaired fasting glucose (IFG).  This condition puts you at a higher risk for developing type 2 diabetes and cardiovascular disease.

What Risk Factors are Associated with Type 2 Diabetes?

Risk factors are most important for conditions that are preventable.  Type 2 diabetes is the only preventable form and includes several risk factors:

• Family history of diabetes
• Unhealthy diet
• Physical inactivity
• Increasing age (people who are over 40 and overweight are more likely to develop the condition)
• High blood pressure
• Ethnicity (diabetes is more common among Native Americans, African Americans, Hispanic Americans and Asian Americans/Pacific Islanders)
• Impaired glucose tolerance (IGT)
• History of gestational diabetes
• Poor nutrition during pregnancy

Obesity and Diabetes

Obesity, particularly abdominal obesity, is linked to the development of type 2 diabetes.  In fact, of the people diagnosed with type 2 diabetes, about 80 to 90 percent are also diagnosed as obese.  Being overweight places extra stress on your body in a variety of ways, including your body’s ability to maintain proper blood glucose levels.  In addition, being overweight can cause your body to become resistant to insulin.  If you already have diabetes, this means you will need to take even more insulin to get sugar into your cells. And if you don’t, the prolonged effects of the insulin resistance can eventually cause you to develop the disease.

According to The Obesity Society (www.obesity.org), If you are overweight, even a small weight loss (five to ten percent) can prevent diabetes – or prolong the chance that you will develop the disease – even if you fall into a high risk category.  If you have diabetes, the same amount of weight loss can reduce the amount of medication needed, as well as help prevent common complications associated with diabetes (i.e., blindness, stroke and heart attacks).

To prevent and better manage diabetes, people who are overweight or obese are encouraged to achieve and maintain a healthy body weight with a healthy diet and regular physical activity.

Physical Activity and Diabetes

In an effort to maintain a healthy body weight, physical activity plays an important role in the prevention of diabetes. Increased physical activity is important maintaining a healthy body weight, and is linked to reduced blood pressure, reduced resting heart rate, increased insulin sensitivity, improved body composition, and overall psychological and emotional wellbeing.

According to the American College of Sports Medicine (ACSM), the chronic effects of physical activity, relating to type 2 diabetes, include:

• Both aerobic and resistance training improve insulin action, blood glucose control, and fat oxidation and storage in muscle
• Blood lipid responses to training may result in a reduction LDLs and no change in HDLs and triglycerides.  Combined weight loss and physical activity may be more effective than aerobic exercise alone.
• Aerobic training may reduce systolic blood pressure (reductions in diastolic blood pressure are less common)
• Greater physical activity and fitness are associated with a lower risk of cardiovascular mortality (and mortality in general)
• Recommended levels of physical activity may help promote weight loss
• Individuals engaged in supervised training exhibit greater compliance
• Increased physical activity and fitness can reduce symptoms of depression and improve health-related quality of life

For the prevention of type 2 diabetes, the ACSM recommends a minimum of 2.5 hours per week of moderate to vigorous physical activity.

• Aerobic training – at least three exercise sessions per week, at a moderate intensity (40 to 60 percent VO2 Max), for a total of 150 minutes of exercise
• Resistance training – at least two exercise sessions per week, at a moderate (50 percent of 1RM) or vigorous (75 to 80 percent of 1RM) intensity, incorporating five to ten exercises involving the major muscle groups
• Other forms of exercise – supervised and combined aerobic and resistance training may provide health additional benefits and flexibility training may be included (but should not be done in place of other recommended types of physical activity)

For more information on the ACSM position statement on exercise and type 2 diabetes, click here.

Diabetes Websites & Resources

For more information on diabetes prevention and management, visit the following websites:

• Joslin Diabetes Center (the world’s largest diabetes research and clinical care organization, affiliated with Harvard Medical School)
• American Diabetes Association
• International Diabetes Foundation – Diabetes Atlas (PDF)