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Pre-diabetes is a very common and treatable condition. Through your physical activity and appropriate diet choices, you have already taken many steps to delay or avoid progression to type 2 diabetes.

Member Question

I just turned 40 and decided it would be a good thing to finally establish a relationship with a primary care physician and have a full checkup. I had blood work done and got my results today. I was shocked to hear that I was pre-diabetic!! I have NEVER been overweight. I am 5'4" tall and 123 lbs. The most I ever weighed was 130 lbs. I work out six days a week: spin, total body conditioning, yoga, running, x-fit. I've been doing sprint tris for a few years and do a few 5k's a year. My diet is healthier than anyone I know. I haven't had a regular soda in over 20 years, I don't eat much candy or desserts.  I look at the sugar content in every yogurt I buy! She told me that in my case it is genetic. I certainly don't want to become diabetic. I am not sure what else I can do to prevent it?  I also want to continue exercising.  Do you have any recommendations?

Answer from Kirk Mulgrew, MD
Member AMSSM 

Dear Prediabetic,

First off, congratulations on your decision to establish a relationship with a primary care physician and obtain a full check-up.  While the results may have been shocking, you are not alone, and you are taking the right steps toward better health through prevention and education.  I will provide a brief discussion on diabetes and pre-diabetes including current guidelines regarding diet, exercise, and medications for the prevention and treatment of diabetes.

Diabetes Mellitus, commonly known as “Diabetes” refers to the body’s inability to maintain blood glucose levels within normal ranges. There are 4 clinical classes of diabetes mellitus:

1 – Type 1 (5-10% of cases) refers to absolute insulin deficiency from autoimmune destruction of insulin secreting cells in the pancreas

2 – Type 2 (90-95% of cases) refers to a defect of insulin secretion as well as the inability of muscle cells to respond to insulin properly (insulin resistance)

3 – Other (including genetic diseases like cystic fibrosis, and medication induced (as in immunosuppressive medications))

4 – Gestational Diabetes Mellitus (GDM), diagnosed in pregnancy, but not true diabetes. Has 40-60% risk of developing diabetes in 5-10 years

Given your age, the relatively higher prevalence of type 2 diabetes, and your primary care physician’s diagnosis, it is likely that the pre-diabetes mentioned in your question refers to your risk of developing type 2 diabetes. As such, the remainder of this topic will deal with type 2 diabetes and pre-diabetes. 

How is diabetes diagnosed?

The diagnosis of diabetes can be made if any of the blood tests below are positive (and confirmed positive on repeat testing):

1 – Hemoglobin A1C (HbA1C) > 6.5 OR

2 - Fasting glucose greater than or equal to 126 OR

3 – A 2-hour plasma glucose greater than or equal to 200 during an oral glucose tolerance test (OGTT = test of blood glucose 2 hours after taking 75 grams of glucose dissolved in water) OR

4 - symptoms of hyperglycemia, or in hyperglycemic crisis with random plasma glucose greater than or equal to 200mg/dL

There are many cases in which blood glucose levels do not fit the above criteria but are higher than normal. These cases fit into the category of pre-diabetes. In fact, 79 million Americans are estimated to have pre-diabetes.  A person is considered to have pre-diabetes if one of the tests below is confirmed to be positive:

1 - Fasting glucose 100-125 (Impaired Fasting Glucose = IFG)

2 - OGTT 140-199 (Impaired Glucose Tolerance = IGT)

3 - HbA1C of 5.7-6.4%

What causes diabetes?

The causes of type 2 diabetes are environmental and genetic. The genetic causes are complex and not completely understood.  Environmental causes are largely related to lifestyle choices including diet and physical inactivity.

Pre-diabetes is a risk factor for diabetes and cardiovascular disease and is often associated with obesity, cholesterol abnormalities, and hypertension.  In addition, if a person has a BMI of 25 or higher and has any of the below risk factors, blood tests should be considered (even if they do not have any symptoms):

1 - Physical inactivity

2 - First-degree relative with diabetes

3 - High-risk race/ethnicity (African American, Latino, Native American, Asian American, Pacific Islander)

4 - Women who delivered baby > 9lbs or were diagnosed with GDM

5 - Hypertension (BP 140/90 or higher, or on meds for hypertension)

6 - HDL cholesterol

7 - Triglycerides > 250

8 - Women with polycystic ovary syndrome (PCOS)

9 - HbA1C of 5.7% or higher, or IFG/IGT on previous test

10 - Severe obesity

11 - Acanthosis nigricans

12 - History of cardiovascular disease

One may also consider testing for individuals age 45 or older. Other considerations for testing include if a person is taking medications like glucocorticoids or antipsychotics (also if taking glucocorticoids and/or antipsychotics

Given your description of working out six days a week and eating a well balanced healthy diet, it is likely that genetics played the largest role in your development of pre-diabetes. It would be important to note if any of the other risk factors above were also present. Given that testing was positive, you should repeat testing every year. If the testing had been negative, repeat testing would be appropriate at least every three years.

How can diabetes be prevented?

In general, most recommendations regarding the prevention and/or delay of diabetes involve lifestyle changes including diet and exercise. Multiple studies have been conducted to provide support for the recommendations listed below:

1 - If someone is pre-diabetic, he/she should be referred to an ongoing support program for weight loss (7% of body weight), and increase in moderate physical activity to 150min/week

2 - Follow-up counseling should occur

3 - Metformin therapy for prevention of type 2 diabetes may be considered in those with pre-diabetes, (especially if BMI >35, age

4 - At least annual monitoring should take place

5 - Screening for and treatment of modifiable cardiovascular disease risk factors should occur

*Other medications, such as alpha-glucosidase inhibitors, orlistat, thiazoledinediones have shown to decrease incidence of diabetes to varying degrees.


There are specific recommendations regarding diet for those at risk for diabetes (summarized below):

- USDA recommendation for fiber intake (14g fiber/1000kcal)

- Foods with whole grains should comprise one-half of total grain intake

- Sugar sweetened beverage intake should be limited

- Saturated fat intake should be

- Intake of trans fat should be minimized (reducing intake of trans fat lowers LDL

cholesterol and increases HDL cholesterol)

- Moderate intake of alcohol (1 drink or less per day for women, and 2 drinks or less per day

for men) may be beneficial 

- Routine supplementation with antioxidants such as vitamin E, C and carotene is not

recommended because of a lack of evidence, and a concern for long-term safety

Studies have compared different diets including low fat, low carb, and Mediterranean diets. One study in Spain showed a reduced risk of diabetes by 52% (in the absence of weight loss) with the Mediterranean diet compared to the low-fat diet.  Another study showed that low carb diets resulted in lower triglycerides and higher HDL cholesterol; however, LDL cholesterol also was significantly higher with the low carb diet.  Also, one must be careful with lower-carb diets, as the long-term metabolic effects of these diets are unclear, and these diets eliminate important sources of energy, fiber, vitamins, and minerals. In general, Mediterranean, plant based (vegetarian, vegan), low fat, and low carb diets are likely to be beneficial. Selection of these diets should be individualized based on personal goals and preferences.

Support through medical nutrition therapy (MNT) with a registered dietician familiar with diabetes MNT has shown promising results. Also, Diabetes Self-Management Education (DSME) and Diabetes Self-Management Support (DSMS) are likely to help with sustained achievement of diabetes prevention goals. More information can be found in the ADA position statement “Nutrition Recommendations and Interventions for Diabetes.”

Physical Activity

Physical Activity is also very important in prevention of diabetes. Both aerobic and resistance training (weight training) improve insulin action, blood glucose control, and fat oxidation and storage in muscle. A single session of aerobic exercise increases insulin action and glucose tolerance for 24-72 hours. Regular exercise should occur at least 150 min/week (50-70% max heart rate) spread over at least 3 days/week with no more than 2 consecutive days without exercise. Resistance training involving all major muscle groups should occur at least 2 times per week. Studies have shown that those who exercise with qualified exercise trainers showed greater compliance and blood glucose control. Results of studies evaluating yoga and tai-chi are inconclusive at this time. The risk of exercise-induced hypoglycemia is very rare (in anyone not taking insulin or insulin secretagogues). Brief, intense aerobic exercise can cause transient hyperglycemia due to the body’s catecholamine release.

Before increasing physical activity to levels more intense than brisk walking, sedentary individuals with type 2 diabetes will likely benefit from an evaluation by a physician. Those with pre-diabetes may want to see their physician before significant changes in their exercise regimen*. Screening tests such as stress EKGs are not routinely recommended; however, a stress EKG may be considered if any of the below risk criteria are met:

1) Greater than 40 years old with or without cardiovascular disease risk factors other than diabetes

2) Greater than 30 years old AND

-type 1 or type 2 diabetes for more than 10 years


-cigarette smoking

-dyslipidemia (abnormal cholesterol)

-proliferative or preproliferative retinopathy

-nephropathy, OR

3) known or suspected coronary artery disease, cerebrovascular disease, peripheral arterial disease, autonomic neuropathy, or advanced nephropathy with renal failure.

*There is no evidence available regarding stress testing before resistance exercise.


Medications that are often used for conditions associated with diabetes may have effects on exercise, including:

Beta-blockers (for hypertension): blunt heart rate responses to exercise, and lower maximal exercise capacity. They may also increase risk of undetected hypoglycemia during exercise.

Diuretics (for hypertension): may result in dehydration and electrolyte imbalances, particularly during exercise in the heat.

Statins (for cholesterol): may increase risk of myalgia (muscle pain) and myositis (muscle inflammation), especially if used with fibrates and niacin.

In summary, pre-diabetes is a very common and treatable condition. Through your physical activity and appropriate diet choices, you have already taken many steps to delay or avoid progression to type 2 diabetes. While many of the above general recommendations may not apply to someone as active as you, I hope that some of the specifics regarding diet and exercise, medication use, and medical resources will help you and your health care team make the best decisions for your future as a triathlete. Keep up the good work and keep on exercising!

Kirk Mulgrew, MD


American Diabetes Association. Standards of medical care in diabetes--2013. Diabetes Care.

2013 Jan;36 Suppl 1:S11-66. 

American Diabetes Association, Bantle JP, Wylie-Rosett J, Albright AL, Apovian CM, Clark NG,

Franz MJ, Hoogwerf BJ, Lichtenstein AH, Mayer-Davis E, Mooradian AD, Wheeler ML. Nutrition recommendations and interventions for diabetes: a position statement of the American Diabetes Association. Diabetes Care. 2008 Jan;31 Suppl 1:S61-78.

Colberg SR, Sigal RJ, Fernhall B, Regensteiner JG, Blissmer BJ, Rubin RR, Chasan-Taber L,

Albright AL, Braun B; American College of Sports Medicine; American Diabetes Association. Exercise and type 2 diabetes: the American College of Sports Medicine and the American Diabetes Association: joint position statement executive summary. Diabetes Care. 2010 Dec;33(12):2692-6


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date: June 7, 2013


The American Medical Society for Sports Medicine (AMSSM) was formed in 1991 to fill a void that has existed in sports medicine from its earliest beginnings. The founders most recognized and expert sports medicine specialists realized that while there are several physician organizations which support sports medicine, there has not been a forum specific for primary care non-surgical sports medicine physicians.



The American Medical Society for Sports Medicine (AMSSM) was formed in 1991 to fill a void that has existed in sports medicine from its earliest beginnings. The founders most recognized and expert sports medicine specialists realized that while there are several physician organizations which support sports medicine, there has not been a forum specific for primary care non-surgical sports medicine physicians.


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