Runners & Diabetes
by J. Lance Tarr, MS, CSCS, SPT
In order to effectively deal with diabetes, either personally or in an attempt to help someone who has the disease, the first line of defense is education. So, let's take a moment and look at some statistics followed by a course of action recommended for a runner with diabetes.
In the last two to three years, the number of those with diabetes in the U.S. has increased by about 1 million. It now stands at roughly 17 million - or 6.2% of the population. Unfortunately, 5.9 million of those individuals have not been diagnosed yet. They don't know anything is wrong.
There are actually four types of diabetes: Type 1 (formerly called insulin-dependent or juvenile diabetes), Type 2 (formerly called noninsulin-dependent or adult onset diabetes), gestational diabetes (which can occur during pregnancy), and specific types which occur secondary to specific genetic syndromes, surgery, drugs, malnutrition, infections and other illnesses. Of these types, 90-95% are Type 2, 5-10% are Type 1. Gestational develops in 2-5% of all pregnancies, although it resolves post delivery. However, women who develop gestational diabetes have as much as a 40% increased risk of developing Type 2 diabetes later in life.
Type 1 diabetes is an auto-immune disease which affects mostly children and young adults. Simply put, the pancreas does not produce insulin; therefore, daily insulin injections are required. Type 2 is a metabolic disorder in which insulin is actually produced, but in insufficient quantity - or what is produced cannot be utilized effectively. Some form of pharmaceutical intervention may be needed, but often proper diet and exercise can control glucose levels and no drug use is required.
Obesity and sedentary lifestyle are common causes of Type 2 diabetes. In fact, for the first time in history, significant numbers of children (prepubescent and adolescent) are being diagnosed with Type 2 diabetes. The incidence of Type 1 diabetes has not changed, but the incidence of Type 2 in children has increased ten-fold over the past two decades.
This is particularly disturbing due to the complications created over a lifetime by diabetes and the high morbidity and mortality rates associated with those complications.
Some statistics on what those complications are should get anybody's attention. Heart disease (the number 1 killer of U.S. citizens) is responsible for 2-4 times the deaths in a diabetic population vs. a non-diabetic population. Risk of stroke is 2-4 times greater, high blood pressure occurs in 73% of the diabetic population, it's the leading cause of blindness in 20-74 year olds (retinopathy), the leading cause of end-stage kidney disease (nephropathy) and the leading cause of non-traumatic amputations. 60-70% of diabetics suffer significant nerve damage causing impaired sensation in feet or hands (neuropathy), increase in periodontal disease, pregnancy complications and biochemical emergencies such as hypoglycemia or ketoacidosis.
The financial cost (aside from the human toll) is staggering. Costs directly related to diabetes treatment runs to $98 billion per year at present.
Exercise, Nutrition and Glucose Level
Exercise, whether undertaken for rehabilitation, fitness or athletic performance, should be measured by quantity, quality and application. Traditionally, these have been referred to as frequency, intensity, duration and mode (FIDM). Frequency is how often, intensity is how vigorous, duration is how long, and mode is in what way is it done. These aspects become extremely important for the individual with diabetes. In addition, there are two other aspects which are critical to a program - the rate of progression and, particularly for those with diabetes, the timing of exercise.
Exercise dramatically affects your metabolism, both during the activity and over the course of day-to-day living. It has both an acute and chronic effect. Since glucose is your primary fuel source, it becomes absolutely essential that anyone with diabetes monitor their glucose frequently, and always test before and after exercise. If exercising longer than 60 minutes, test during exercise. In addition, always carry a fast-acting glucose with you - glucose tablets, Lifesavers, raisins, etc. - as well as a medic alert tag. It's an excellent idea not to exercise alone as well.
It is important to note that a given response by an athlete with diabetes may be significantly different on another occasion, even though glucose levels, feeding and FIDM of exercise are the same. Over time and through continued education, you should become expert at your own management of diabetes, in conjunction with your physician, certified diabetic educator (CDE) and other qualified health care professionals. Ultimately, however, the primary responsibility for management lies with the individual who has the disease. Acute awareness of the body's signs and symptoms as well as an understanding of what to do if a glucose emergency arises is vital to avoiding a life-threatening situation.
It is unlikely that most recreational athletes will undertake exercise sessions lasting longer than 1-2 hours 4-6 days per week. A dietary mix of 65% carbohydrate, 25% fat, and 10% protein should be adequate to maintain carbohydrate (CHO) stores. The timing of food intake and energy expenditure becomes one of the most critical points. Additionally, hydration status becomes critical secondary to heat intolerance due to poor thermoregulatory mechanisms (sweat control) and vasomotor compromises (increased risk for hypotension due to poor control of blood vessels and drop in blood volume due to sweating). Therefore, fluid intake should match fluid loss during and post exercise.
Endurance athletes who are exercising more should concentrate on consuming 8-10 grams of carbohydrate per kilogram of body weight per day, 1.2g of protein/kg/day, and the remaining balance of energy from fat.
Exercise recommendations based on pre-exercise blood glucose levels follow; however, these are only guidelines. You will need to fine-tune each criteria to fit your unique body chemistry.
Less than 70 ml/dl Do not exercise. Eat 25 to 50 grams of CHO and re-check glucose in about 20 minutes. 70 to 100 ml/dl Eat 25 to 50 grams of CHO before exercise such as a half-sandwich plus a milk or fruit exchange, then 10 to 15 grams during each hour of exercise. (More than one hour of exercise increases the risk of hypoglycemia, which can occur 24 to 48 hours after an exercise session.) 100 to 170 ml/dl Exercise. Eat 10-15 grams of CHO such as fruit or milk during each hour of exercise. 170 to 300 ml/dl No increase in food necessary unless you exercise for more than an hour. Above 300 ml/dl Postpone exercise and check urine for ketones (strips are available at the pharmacy) if you are a Type 1. Do not exercise until your blood sugar is under better control.
Improvements in the control of diabetes through resistance training have been demonstrated in various studies. Improvements in oral glucose tolerance, fasting plasma insulin and glycemic control have all been documented. Care must be taken to avoid heavy loads, avoiding a valsalva maneuver (holding of breath) and maintaining the head above the heart as a few key points.
W.G. Hornsby, author of Resistance Training, The Health Professional's Guide to Diabetes and Exercise (1995) notes that, "Attention to modifications in training, such as lowering the intensity of lifting, eliminating exercise to the point of exhaustion and limiting the amount of sustained gripping or isometric contractions may be useful in reducing exercise-induced blood pressure elevations."
In addition, weight training may be contraindicated for those with diabetic retinopathy. Make sure you've checked with your physician before embarking on any exercise regimen.
Running can be an invaluable tool in the control of diabetes. However, please be advised that running is a high-impact activity. It can cause damage to the feet, which are already vascularly compromised by the disease. It may not be the best mode of exercise for the diabetic when legitimate, less risky alternatives exist. Only you and your health care team can decide if you should run - and how far/how often you should run.
Diabetes is a chronic disease. There is presently no cure. However, with intelligence and action, it can be effectively controlled and complications significantly delayed if not avoided.
Visit the American Diabetes Association.