April 4, 2014
News Review From Harvard Medical School -- Diet, Exercise Cut Death Rates in Pre-diabetes
People with blood sugar just below diabetes levels may live longer with diet and exercise, a new study has found. The study included 438 people who were randomly assigned to a program of diet and exercise and 138 who did not make specific changes. All of them had pre-diabetes. This condition is defined by blood-sugar levels that are above normal but not as high as those in diabetes. But people with this condition have a high risk of developing type 2 diabetes. Diet and exercise, including weight loss, can lower the odds of developing type 2 diabetes in people with pre-diabetes. People with type 2 diabetes have twice the average risk of dying from heart disease or stroke. In this new study, researchers kept track of people for about 20 years. About 12% of those in the diet and exercise group died of heart disease, stroke or related causes. The death rate was about 20% in the group that did not make lifestyle changes. Death rates from any cause were 28% in the diet and exercise group and 38% in the other group. The journal Lancet Diabetes & Endocrinology published the study online April 3. HealthDay News wrote about it.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
An estimated 79 million adults in the United States have pre-diabetes. If you have pre-diabetes, your blood sugar is higher than normal. But it's lower than the number used to diagnose diabetes.
How is pre-diabetes diagnosed? Here is what the American Diabetes Association says:
- Normal blood sugar means having a fasting blood sugar below 100 milligrams per deciliter (mg/dL) or a hemoglobin A1C below 5.7%.
- Pre-diabetes means having a fasting blood sugar between 100 and 125 mg/dL or an A1C between 5.7% and 6.4%.
- Diabetes is diagnosed when you have at least 2 fasting blood sugar readings of 126 mg/dL or higher or a single A1C of at least 6.5%.
A fasting blood sugar is measured by a simple blood test. Before the test, you must have nothing to eat or drink other than plain water for at least eight hours. But it's just one snapshot of what's happening to your blood sugar levels. That's why more than one test is needed before diagnosing diabetes.
An A1C is also a simple test. It looks at your red blood cells. It measures the percentage of oxygen-carrying hemoglobin molecules on these cells that have glucose attached to them. The test can be done any time of the day. It does not require fasting or any other changes in diet. The advantage of an A1C test is that it reflects your average blood sugar level during the last two to three months. That's why it needs to be done only once to make a diagnosis.
Most people with pre-diabetes will develop type 2 diabetes. But it's well known that serious lifestyle changes can lower the risk. And if you do stay physically active and maintain a healthy weight, that will do much more than just lowering blood sugar levels.
If you have pre-diabetes, diet and exercise greatly increases your chance of living longer. In this study, some people were assigned to a 6-year lifestyle change program. Over 20 years, they had a 10% lower death rate than those in a group that made no changes.
What Changes Can I Make Now?
Get tested for pre-diabetes. The American Diabetes Association recommends either a fasting blood sugar or an A1C test every 3 years for people ages 45 and older. People who have a higher risk of diabetes should begin testing earlier and repeat the tests as often as yearly. Factors that increase diabetes risk include being overweight, having a parent or sibling with type 2 diabetes, or having high blood pressure or high cholesterol levels.
Watch your diet. Most important is maintaining a healthy weight. Ideally this means a body mass index (BMI) of less than 25. But at least make sure you keep it under 30. (Obesity is commonly defined as a BMI of 30 or more.).
There is no best diet to prevent diabetes. Reducing total calories and limiting simple sugars matter the most. Recent studies suggest that a Mediterranean-style diet might be the way to go.
Get active. The more you move, the better your chance of avoiding pre-diabetes and diabetes. Set aside at least 30 minutes every day as dedicated exercise time. Work your way up to 45 to 60 minutes most days of the week.
What Can I Expect Looking to the Future?
These study results were to be expected. It's well known that the same lifestyle choices that help prevent diabetes also reduce the risk of heart attack, stroke and early death.
Is the message being heard? Surely not often enough. But recent estimates that show a potential slowdown in rising obesity rates do offer hope.