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Clients, Diabetes, and Exercise - How Ready Are You?

by By Fabio Comana, MA, MS, NASM CPT, CES & PES | Nov 15, 2012

Millions of Americans have diabetes, and many don’t even know it yet. Discover the important role exercise can play in managing this disease and what signs to watch for when training diabetic clients during the American Diabetes Month of November.

Diabetes mellitus represents a group of metabolic diseases affecting over 25.8 million people (8.2% of the U.S. population) with 1.9 million new adult cases diagnosed in 2010. This disease is not exclusive to adults as approximately 1 in 400 children and adolescents have this disease as well.  In 2007, diabetes contributed to a total of 231,404 deaths, and totaled $218 billion in medical costs. Diabetes is the leading cause of adult blindness and kidney failure. Almost 70% of diabetics develop some form of nervous system damage, and they also experience a 2 – 4 time higher death rate from heart disease.

Diabetes often goes undiagnosed because many symptoms seem harmless, but early detection and treatment can decrease the chances of complication. Various methods are used to detect the disease, including measuring fasting (8-hour) blood glucose levels.                          

  • Before developing type 2 diabetes, most people develop pre-diabetes due to elevated blood glucose levels. Research demonstrates long-term heart and circulatory system damage occurs during pre-diabetes, but the Diabetes Prevention Program (DPP) study conclusively demonstrated that dietary and exercise programming (30 minutes daily), coupled with about a 7% reduction in body weight produced a 58% reduction in diabetes risk.
  • Type 1 diabetes is generally caused by an autoimmune destruction of insulin-producing beta cells in the pancreas and accounts for 5% of all diabetes cases. Here, the body fails to produce insulin, thus the uptake of glucose and other foods into cells is hindered as insulin is an anabolic or storing hormone. This increases the propensity for ketoacidosis (discussed shortly) and is marked by:
    o Frequent urination
    o Unusual thirst and extreme hunger
    o Unusual weight loss
    o Extreme fatigue and irritability
  • Type 2 diabetes is the most common form of the disease and is attributed to an insulin deficiency or insulin resistance by cell wall receptors. The insulin present is unable to transfer glucose into the cells, causing the body to keep increasing insulin levels in the bloodstream in an effort to transport the glucose into the cells, resulting in an elevated level of both circulating insulin and glucose. This disease is marked by:
    o Any of the type 1 symptoms
    o Frequent infections
    o Wounds that are slow to heal
    o Blurred vision
    o Tingling/numbness in the hands/feet
    o Recurring skin, gum, or bladder infections
  • Gestational diabetes is another form, typically developing during the second half of pregnancy in previously non-diabetic women. Symptoms are similar to type 1 diabetes, but they can be mild or non-existent. Blood sugar levels will usually return to normal after delivery; however, there is an increased risk for these women to develop type 2 diabetes in the future.

Managing diabetes requires a structured lifestyle program of education, dietary modification, and regular physical activity that targets an initial 5 - 7% weight loss. The overall nutritional goals are to maintain optimal blood glucose levels (or as close to normal as safely possible) and improve health (prevent and /or treat diabetes complications, obesity, dyslipidemia, cardiovascular disease, hypertension, and nephropathy) by modifying nutrient intake and making healthy food choices, while addressing individual nutritional needs and preferences. This includes carbohydrates from whole grains, fruits, vegetables, dried beans and low-fat milk; monitoring the glycemic effect of carbohydrates, but more importantly monitoring the glycemic load (combination of glycemic index and amount of carbohydrates consumed in meals or snacks). It is important to remember that a number of factors influence the glycemic response of food and these should be examined closely when working with a diabetic client. Diabetics should always consult with a registered dietitian, but the fitness practitioner should assume a support role as a nutritional educator.

Regular physical activity improves insulin resistance and blood glucose management, and reduces many of the health complications associated with diabetes. Before engaging in an exercise program, diabetic clients should undergo a detailed medical evaluation with their medical provider to assess risks versus benefits of exercise.  Aerobic-type activities sensitize insulin receptors more effectively than anaerobic exercise, so cardio exercise is initially recommended. Plan to start slowly with 10-minute incremental bouts and select enjoyable activities. Although type 2 diabetics are often overweight and guidelines recommend 5 – 7 bouts of exercise a week, fitness professionals should first plan to implement a manageable, progressive program that fits their abilities and lifestyle.  Always monitor blood pressure responses and watch for symptoms of hyperglycemia, ketosis, hypoglycemia, and neuropathies/foot issues (development of blisters – suggest using soft inserts, keeping feet dry at all times, using polyester or blend socks, and starting with non-weight bearing activities).

During exercise, hyperglycemia (elevated blood glucose) rarely occurs in healthy individuals because of hormonally-mediated responses that are essentially lost in diabetics. The action of counter-insulin hormones during exercise normally elevate blood glucose levels, but as glucose cannot enter cells, blood levels increase and this will ultimately elevate ketone body levels as well. Ketones are the result of incompletely metabolized fats and proteins in cells due to insufficient glucose available within cells to facilitate their metabolism – this can precipitate ketoacidosis, a serious condition that can lead to coma or death.  Early symptoms of ketoacidosis include increased thirst, dry mouth, frequent urination, high blood and urine glucose/ketone levels, constant fatigue, fruity-smelling breath, and reduced mental alertness. Ketone levels in urine can be detected through a simple urine strip test provided through a healthcare provider. Although exercise generally lowers blood glucose levels, if pre-exercise glucose levels exist above 240 mg/dL, urine ketone levels should always be checked, and if present the individual should contact their healthcare provider immediately.


Conversely, the presence of high levels of insulin due to exogenous administration (e.g., injection or pump-release timing) or consuming high-glycemic loads too close to exercise can inhibit glucose mobilization from liver cells that may trigger hypoglycemia. Symptoms of hypoglycemia include shakiness, dizziness, sweating, hunger, headache, pale skin color, sudden mood or behavior changes, clumsiness and mental confusion. An efficient means to quickly raise blood glucose is to administer 15 – 20 grams of a high-glycemic sugar or carbohydrate food (e.g., energy drink, sweets).


Although diabetes is a serious metabolic disease best monitored by medical professionals, the growing prevalence of this disease is dictating a need for fitness professionals to become part of this healthcare continuum. Consequently, it is important to fully understand this group of diseases – the pathology, complications and therapeutic modalities.



  1. American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription 8th ed. Philadelphia: Lippincott, Williams & Wilkins; 2010.
  2. American Diabetes Association.  2011 National Diabetes Fact Sheet. http://www.diabetes.org/diabetes-basics/diabetes-statistics/ 26 Jan. 2011 Date accessed 24 Oct. 2012.
  3. Glucose. http://labtestsonline.org/.  23 Mar 2012. Date accessed 30 Oct. 2012.
  4. Leena A. Ahmad, MD, and Jill P. Crandall, MD. Type 2 Diabetes Prevention: A Review. Clin Diab 31 Mar. 2010;28(2)53-59 online. http://clinical.diabetesjournals.org/content/28/2/53.full Date accessed 29 Oct, 2012
  5. Diabetes. http://www.mayoclinic.com/health/diabetes/DS01121 25 Jan. 2012 Date accessed 30 Oct. 2012.