Lifestyle Strategies for Preventing Type 2 Diabetes

By Paul E. Lemanski, MD, MS, FACP

Editor’s Note: This is the 109th in a series on optimal diet and lifestyle to help prevent and treat disease. Any planned change in diet, exercise or treatment should be discussed with and approved by your personal physician before implementation. The help of a registered dietitian in the implementation of dietary changes is strongly recommended.

Medicines are a mainstay of American life and the health care system, not only because they are perceived to work by the individuals taking them, but also because their benefit may be shown by the objective assessment of scientific study. Clinical research trials have shown that some of the medicines of Western science may reduce the risk of Type 2 diabetes, heart attacks, strokes and cardiovascular death.

In the first 108 installments of the Non-Medicated Life, certain dietary practices and a healthy lifestyle have been shown to accomplish naturally for the majority of individuals most of the benefits of medications in the prevention and treatment of chronic medical conditions. This is especially true for prediabetes, a condition present for several years prior to the development of Type 2 diabetes. This is especially important as Type 2 diabetes greatly increases the risk of heart attacks and strokes, and nearly 75 million Americans have prediabetes.

So how do you know if you have prediabetes? The easiest way to suspect you may have this condition is to use family history and body weight. If Type 2 diabetes is present in ANY of your family members, but especially first-degree relatives – mother, father, sister or brother – you are at risk. Additionally, if you are overweight or obese, then you are at risk. Overweight or obese may be scientifically determined by using body mass index (BMI) calculator: cdc.gov. Overweight is a BMI between 25-30 and obese is a BMI greater than 30.

If a suggestive family history or elevated BMI (or both) are present, then the next step to determining if one has prediabetes is targeted blood tests. The two most important blood tests are a blood glucose after a 12-hour fast, Fasting Blood Sugar (FBS) test, and a hemoglobin A1c (Hgb A1c) test. Additionally, prediabetes may be determined at its earliest stages – even without an elevation of FBS or Hgb A1c – by identifying a condition called metabolic syndrome. Let’s describe each determination in turn:

If the FBS is greater than 99 milligrams per deciliter (mg/dl), but less than 126, then this is the most common test to suggest prediabetes. An even more exacting way of determining prediabetes is an elevated Hgb A1c. Hemoglobin is an iron containing protein present in red blood cells (RBCs) that binds oxygen in the lungs and transports it to the tissues of the body. By serendipity, hemoglobin also binds glucose and the RBCs are permeable to glucose. Hgb A1c, therefore, is the percent of hemoglobin in the RBCs bound to glucose. Hgb A1c less than 5.7% is normal, Hgb A1c 5.7-6.4% is prediabetes, and Hgb A1c greater than 6.4% is diagnostic of Type 2 diabetes. Since RBCs have a lifespan of three months, Hgb A1c reflects the average blood sugar over the preceding three months.

Both prediabetes and Type 2 diabetes are metabolic conditions that reflect insulin resistance. Insulin is a hormone produced in the islet cells of the pancreas that is released into the blood stream. The insulin fits into a receptor on the surface of the body’s cells that in turn activates a “pump” that takes glucose from the blood stream and transports it into the cell. The underlying metabolic derangement in both conditions may be a change in the shape of the receptor requiring increased amounts of insulin to activate the pump. This state of increased insulin may be determined even before the blood glucose is elevated by identifying metabolic syndrome.

Metabolic syndrome is defined as any three of the following conditions: 1) an elevated fasting Triglyceride (TG greater than 150); 2) a reduced HDL cholesterol (less than 40 in a male and less than 50 in a female; 3) an elevated Blood Pressure (BP) or on BP lowering medications; 4) an increased abdominal girth at the umbilicus (aka belly button) (greater than 35 inches in female and greater than 40 inches in male); and 5) an elevated FBS. It is apparent that if any three out of five make the diagnosis of metabolic syndrome, then an elevated FBS need not be part of making the diagnosis, thus allowing identification of prediabetes even BEFORE blood glucose is elevated.

Once prediabetes is identified, there are powerful lifestyle-based strategies to prevent the progression to Type 2 diabetes and even to reverse prediabetes. Moreover, these strategies are not draconian or overly restrictive, and should be achievable by most interested, reasonably motivated individuals.

The first lifestyle-based strategy is modest weight loss. In the diabetes prevention program trial, the loss of only 5-7% of the body weight of an overweight or obese individual with prediabetes could reduce the development of Type 2 diabetes by 57%. For example, a 5-foot, 2-inch female weighing 200 pounds would need to lose only 10-14 pounds to powerfully protect against the development of Type 2 diabetes, even though she was almost 60 pounds above her ideal body weight. While this weight loss may be achieved by caloric restriction either by a change in the composition of the diet or reduction in the amount of food consumed, or both, it is a strategy many can successfully employ. Alternatively, exercise – both aerobic and resistance activities – while monitoring and holding caloric intake steady, can aid in such modest weight loss.

The second lifestyle-based strategy is time limited eating. While also called intermittent fasting, time-limited eating involves consuming calories for only a set number of hours a day and NOT taking in anything caloric-either food or drink-for the remainder of the 24-hour period. Typically, time-limited eating does not change the composition of your diet or the amount you consume. Rather, it is the timing of eating that is important. On a so called 16/8 time-limited eating plan, you confine all calories consumed to an eight-hour period – generally, 12-8pm – and eat or drink nothing caloric for the remainder of the 24-hour period. Amazingly, with this very simple and implementable change, weight is reduced, abdominal girth is reduced, blood pressure is reduced, cholesterol is improved, and blood sugar is reduced.

In summary, Type 2 diabetes is preceded by several years of prediabetes during which simple lifestyle-based strategies can prevent progression to Type 2 diabetes and even reverse prediabetes. The first step in preventing Type 2 diabetes is to identify prediabetes. Concern should be raised by a family history of Type 2 diabetes or the presence of BMI greater than 25, or both. The next step is the measurement of Fasting Blood Sugar and Hemoglobin A1c tests. Finally, identifying the condition called metabolic syndrome may allow the identification of prediabetes even before the elevation of blood sugar. Once prediabetes is identified, modest weight loss, exercise, and time-limited eating are effective lifestyle-based strategies for preventing Type 2 diabetes.

Paul E. Lemanski, MD, MS, FACP (plemanski3@gmail.com) is a board-certified internist practicing internal medicine and lifestyle medicine in Albany. Paul has a master’s degree in human nutrition, he’s an assistant clinical professor of medicine at Albany Medical College, and a fellow of the American College of Physicians.