If you like numbers and statistics, especially those about health, two reports released this week should keep you occupied for days: the massive Global Burden of Disease study was published in The Lancet, and the American Heart Association released its annual “Heart and stroke statistics” report. The Global Burden of Disease project found that average life expectancy continues to rise in most countries. It also found that infection and other communicable causes of disease no longer dominate deaths and disability. Today, so-called non-communicable causes like traffic accidents, violence and war, heart disease, cancer, and other chronic conditions account for two-thirds of world deaths and the majority of years lost to disability and death. According to the American Heart Association’s annual report, the percentage of deaths due to heart attack, stroke, and other cardiovascular diseases has fallen by nearly one-third since 1999, but don’t expect that to continue. Increases in high blood pressure, high cholesterol, diabetes, overweight, and inactivity threaten to reverse these gains.
Many medical studies confirm what we know or suspect. Every once in a while, though, one surprises us, turning “conventional wisdom” on its head. That just happened with the sudden shutdown of a long-running diabetes trial called Look AHEAD (Action for Health in Diabetes). Begun in 2001 and scheduled to last another two years, Look AHEAD was designed to see if an intensive diet and weight loss program could reduce the number of heart attacks, strokes, and other cardiovascular problems in people with type 2 diabetes. An early peek at the data showed that the program had little apparent effect, and the investigators concluded it would be futile to continue. This does not mean that we should ignore diet and exercise in treating of type 2 diabetes. Instead, the details of the study results, which haven’t yet been published, are likely to reveal other explanations.
As part of its 200th anniversary celebration, today’s New England Journal of Medicine carries an article called “The Past 200 Years in Diabetes.” It describes some of the advances made in understanding and treating this disease, like the discovery of insulin and the development of personal blood-sugar monitors. But it doesn’t tell much about how living with diabetes has changed. Just 50 years ago, checking blood sugar and administering insulin were big ordeals, and people with diabetes weren’t expected to live more than a few years after their diagnoses. today, it’s a cinch to check blood sugar with a quick finger prick, and pen-like devices almost painlessly deliver insulin, and people with diabetes who take care of themselves have almost normal life expectancies. Advances in protecting and treating the heart, eyes, kidneys, and limbs have helped reduce complications from diabetes.
Picture an old-fashioned roller coaster with plenty of ups and downs. That’s what your blood sugar and insulin levels look like over the course of a day. The highs that follow meals and snacks drop to lows later on. Learning to eat in a way that makes your blood sugar levels look more like a kiddie coaster with gentle ups and downs than a strap-‘em-in, hang-on-tight ride with steep climbs and breathtaking drops can make a difference to your health. How can you do this? A tool called the glycemic index (GI) can help. It rates carbohydrate-containing foods by how much they boost blood sugar (blood glucose). Using the glycemic index to choose a healthier diet is easier than you might think. Focus on foods with a low glycemic index (55 or less), and try to limit those with a high glycemic index (70 or higher).
We tend to think of type 2 diabetes as a disease that afflicts people who are overweight. But it can also appear in people with perfectly healthy weights—and be more deadly in them. A study published in the Journal of the American Medical Association indicates that normal-weight people diagnosed with type 2 diabetes have double the risk of dying from heart disease and other causes than overweight people with diabetes. Such apparent “protection” by excess weight has been called the obesity paradox. It’s been seen with other conditions, like heart failure and end-stage kidney disease. That doesn’t mean gaining weight is a healthy strategy. Instead, it probably means that something else besides weight—like the amount of fat around the waist—may be contributing to the onset and severity of type 2 diabetes. These new findings underscore the importance of strength training for everyone, no matter what their weight.
Exercise makes cells burn extra energy—that’s one way it helps control weight. It also generates a newly discovered hormone, called irisin, that transforms energy-storing white fat cells into energy-burning brown fat cells. Irisin also appears to help prevent or overcome cellular changes that lead to type 2 diabetes. The hormone does this by helping transform energy-storing white fat cells into energy-burning brown fat cells. White adipose tissue, more commonly known as body fat, is the tissue that dimples thighs, enlarges waists and derrieres, and pads internal organs. Each white fat cell stores a large droplet of fat. Brown fat, in comparison, is chock full of energy-burning mitochondria. Its main function is to generate body heat by burning fat. A team led by Dr. Bruce Spiegelman, professor of cell biology and medicine at Harvard Medical School, has identified irisin in mice and humans and showed how irisin transforms white fat cells into brown ones, at least in mice.
The hemoglobin A1c reading is an important number for people with diabetes. It’s a measure of the average blood sugar level over the preceding three months. For years, the American Diabetes Association recommended that almost everyone with type 2 diabetes should aim for an HbA1c level less than 7%. Keeping blood sugar as low as possible, called “tight control,” was thought to limit the havoc caused by diabetes. New guidelines from the American Diabetes Association (ADA) and European Association for the Study of Diabetes recommend taking a more “patient-centered approach.” For people who are newly diagnosed with type 2 diabetes but who are otherwise in good health, the ADA still suggests aiming for an HbA1C of 6.0% to 6.5%. For people who have had diabetes for a while, an HbA1c goal of 7.5% to 8.0%, or even higher, may be more appropriate.
Sleeping poorly night after night—because you are trying to burn the candle at both ends or you work night or rotating shifts—has long-term health consequences. People who don’t average at least six hours of sleep a night are more likely to be overweight or develop various medical problems. New research from Harvard-affiliated Brigham and Women’s Hospital shows that lack of sleep plays a complex and powerful role in the development of type 2 diabetes. Among volunteers who lived in a sleep lab for several weeks, their bodies made less insulin after meals when they got under 5.5 hours of sleep a night for three weeks. As a result, their blood sugar levels went haywire. Some of the people had blood sugar levels high enough to have been diagnosed as prediabetic.
The term “personalized medicine” is still something of an abstract idea. In an audacious experiment, Stanford molecular geneticist Michael Snyder gave it a face—his own—and showed what it can do. Snyder and a large team of colleagues first sequenced his DNA, revealing his complete genetic library. Then they analyzed blood samples he gave every few weeks for two years. This was akin to taking a 3-D movie of his inner workings to observe how genes, the molecules that read and decode them (RNA), the proteins they make, and other substances interact during health and illness. The team saw how Snyder’s body responded to a cold at the very beginning of the study. Midway through, they watched as molecular changes wrought by a respiratory infection tipped him into full-blown diabetes.