Case Study: The Prevention of Diabetes Through Diet and Intense Exercise

L.H. is a 46-year-old married Hispanic man who sees his primary physician for scheduled diabetes screening. Although he is overweight (6 feet tall, 206 lb, BMI 27.8 kg/m²) and on medication to control his blood pressure, L.H. has no evidence of coronary heart disease or any family history of diabetes. However, last year his fasting glucose level was 122 mg/dl. Two weeks before his appointment, a random glucose test performed with a blood glucose meter at a local health fair revealed 180 mg/dl. At the time of his appointment, routine laboratory results indicate slightly elevated lipids: LDL cholesterol 142 mg/dl and total cholesterol 200 mg/dl. Fasting glucose is 154 mg/dl. Once an avid runner, L.H. has become less physically active in the past year, and his exercise consists of ∼ 300 minutes of low-intensity physical activity per week.

L.H. typically eats 2 cups of cereal, 12 oz. of low-fat milk, and a large apple for breakfast. His lunch consists of one turkey or ham sandwich and one large apple. His main meal is a late dinner of large portions of Mexican food (such as enchiladas with rice), low-fat milk, and cookies. His average daily caloric intake obtained from three different 24-hour recalls was 2,300 kcal.

After the evaluation, the primary physician explains the risks of diabetes and the importance of lifestyle modification to L.H. The physician also explains that an oral glucose tolerance test could be ordered to confirm a diagnosis of diabetes. The physician challenges L.H. to start an intense exercise program and make lifestyle modifications. L.H. is also referred to a registered dietitian for medical nutrition therapy. A 2-month follow-up appointment is scheduled.

1. What type of lifestyle modification should be prescribed for L.H.?

2. What was the outcome after 2 months of treatment?

3. Can risk factors for diabetes be reversed in a short period of time with intense exercise and diet?

Because of his athletic history, L.H. was placed on an intense exercise program that consisted of running on a treadmill 40 minutes/day, six days per week. After nutritional assessment and intervention, L.H. followed an 1,800 kcal/day meal plan. Food items such as flaxseeds, wheat germ, pecans, cinnamon powder, and skim milk were included with the morning cereal. Lunch remained the same as before. Dinner, now scheduled at 6:00 p.m., consisted mostly of baked fish fillet or salmon, steamed rice, and vegetables. A bedtime snack included low-fat milk and a granola bar. The intense exercise program and diet was composed of an average caloric deficit of 1,000 kcal/day (500 kcal from food intake and 500 kcal burned on the treadmill).

Aware of the adverse effects of diabetes, L.H. was committed to his treatment and was able to lose 7% of his body weight. The average weekly weight loss was 2 lb. His BMI after 2 months of exercise and diet was 25.8 kg/m². Laboratory results for his follow-up appointment revealed a fasting glucose of 109 mg/dl, LDL cholesterol of 93 mg/dl, and total cholesterol of 146 mg/dl. During the second month of the treatment period, his blood glucose was monitored and the 2-hour postprandial values were in the range of 97–102 mg/dl.

In the 2-month period of treatment, an average of 1,000 kcal/day deficit allowed L.H. to lose 16 lb and to normalize his lipid profile, fasting glucose, and postprandial glucose levels. Motivation, diet, and intense exercise were crucial for L.H. in preventing a positive diabetes diagnosis by the time of his follow-up appointment. A weight loss of 16 lb could not have been achieved with the low-intensity exercise regimen L.H. was on during the previous year, and a positive diagnosis for diabetes could not have been prevented within the 2 months before the follow-up physician’s appointment.

The patient was determined to make lifestyle changes, and motivation was a critical factor in preventing diabetes. For individuals at high risk, such as L.H., intensive lifestyle modification including a healthy diet and increased physical activity are crucial to prevent the onset of type 2 diabetes. The major dietary change in this case was decreasing caloric intake through portion control. For many patients, dietary intervention must also focus on reducing dietary fat intake, although for L.H., dietary fat intake was within recommended levels.

The major physical activity change for L.H. was a fairly intensive level of caloric expenditure, achieved by 40 minutes/day, six days per week of running on a treadmill. Many patients may not be able to achieve this level of physical activity, but this was reasonable for L.H. because of his athletic background. In addition to lifestyle changes, another treatment option for patients such as L.H. could be the use of a hypoglycemic agent such as metformin.

Extensive studies such as the Diabetes Prevention Program have compared lifestyle intervention with hypoglycemic agents and concluded that lifestyle changes are more effective than therapeutic agents. In order to potentially reverse diabetes risk factors, a 7% weight loss incentive and at least 150 minutes of physical activity per week has been recommended.

In a study conducted by Heled et al.,1 three treatments were used to test the hypothesis that exercise training might prevent diabetes in Psammomys obesus (rodent animal models used to study diet-induced type 2 diabetes). The treatments included a high-energy diet, a high-energy diet plus exercise, and a low-energy diet, with protein kinase C-δ activity being measured. Conclusions from that study demonstrated for the first time that exercise training effectively prevented the progression of type 2 diabetes in Psammomys obesus. The study suggested that a mechanism involving protein kinase C-δ, a group of enzymes that enhance glucose transport, may be involved in the adaptive effects of exercise in skeletal muscles that lead to the prevention of type 2 diabetes.

• Lifestyle modification including increased physical exercise and healthy diet can result in lower rates of diabetes.

• Patients’ motivation is crucial to reversing diabetes risk factors.