NOVEMBER / DECEMBER 2003

FORUM

A silent epidemic takes center stage

One of the deadliest diseases ever known has also been one of the most silent. While the last 15 years have produced an onslaught of public awareness about preventing HIV/AIDS, breast cancer, and prostate cancer, the fact is that diabetes kills more people worldwide than all of these diseases. Compare the world’s 45 million people with HIV/AIDS with its 144 million diabetics. And it’s getting worse—much worse. The World Health Organization predicts that this number could more than double to a staggering 300 million people within 25 years.

Why is this happening? And what can be done to stop it? With November 14 dubbed “World Diabetes Day” by the International Diabetes Foundation (IDF), HMI World talked with scientists from the Harvard-affiliated Joslin Diabetes Center: Dr. Martin J. Abrahamson, Chief, Section on Adult Diabetes; and Dr. Ramachandiran Cooppan.

A problem of global proportions
More than 90 percent of the world’s diabetics suffer from type 2—also known as “adult onset”—diabetes. And because type 2 diabetes is associated with obesity and overweight, it’s only logical to assume that the problem is most prevalent in the United States, the most overweight nation on earth. While the U.S. does indeed carry one of the world’s largest diabetic populations (over 15 million), the IDF reports that the five countries with the highest diabetes prevalence in the adult population are Papua New Guinea, Mauritius, Bahrain, Mexico, and Trinidad & Tobago. One in five of the world’s diabetics are Indian. Occurrences could triple in Africa, the Mediterranean, the Middle East, and Southeast Asia over the next 25 years.

Dr. Martin J. Abrahamson

Dr. Abrahamson says that globally, diabetes has risen in tandem with obesity. “It’s a question of obesity and a more sedentary lifestyle. As more and more countries become developed and as we see this evolution to more fast food, more convenience, and more technologies, we’re seeing decreasing physical activity and increasing overweight and obesity. And the majority of those with type 2 diabetes are overweight or obese.”

The insulin disease
To understand the connection between obesity and type 2 diabetes, it’s important to understand the role of insulin. Whenever we eat, the carbohydrates from our food are broken down into glucose, a sugar that fuels the body’s cells. That glucose is transported throughout the body through the bloodstream to be delivered to the cells. However, in order to allow the glucose into those cells, a “key” is needed: insulin, a hormone produced by the pancreas.

Diabetes is the result of a body without sufficient insulin supplies. In some cases, the pancreas simply doesn’t produce enough insulin (and in some cases, produces no insulin at all) to meet the body’s needs. This is type 1, or “insulin-dependent” diabetes, and it usually occurs at a younger age, possibly the result of an immune reaction.

Type 2 diabetes, on the other hand, results when the body is resistant to insulin. While genetics play an important role in determining who will develop diabetes, certain people develop an insulin tolerance through overeating. “Weight gain corresponds to insulin resistance,” says Abrahamson. “The cells of the pancreas secrete less insulin, and not enough insulin is produced to overcome the body’s resistance.”

A “not-so-equal-opportunity” health crisis
“ While the U.S. has the largest number of overweight and obese people as a nation,” said Dr. Cooppan, “our diabetes rates vary depending on the ethnic group being studied.” The Pima Indians in Arizona, for example, have a disproportionately high rate of type 2 diabetes. Hispanics (living in, and outside of, the U.S.) and African-Americans are considered higher risk groups. While these groups tend to be poorer on average, and thus have less access to quality health care and are less likely to exercise and prepare healthy foods, Cooppan asserts that while “there are certain high-risk ethnic groups predisposed to diabetes, to date it has been very difficult to identify any specific genetic markers. In most cases, diabetes is likely a polygenic disorder.”

“ What’s interesting,” said Abrahamson, “is that the disease is relative. In a country like China, where diabetes is increasing in prevalence, the people are typically thinner than Americans. The increase in weight is not at the same magnitude, and by our standards, they might not even be considered overweight at all.” However, evidence now indicates that visceral or abdominal obesity is more closely associated with insulin resistance and glucose intolerance than other forms. That means that in some parts of the world, such as India and Southeast Asia, people have a Body Mass Index in the desirable range, but the precise location of the body’s fat can promote insulin resistance.

Type 2 diabetes shows no preference for age either. Though the problem has historically affected people aged 40 and higher, more and more adolescents and even young children are developing the disease, a trend spurred largely by the explosive growth of the world’s overweight child population.

The silent killer
One of the reasons that the disease has been able to spread as it has is its stealth attack. More than half of type 2 diabetics are unaware that they have it. How can that be? Cooppan explains that “the disease comes on slowly over years and patients don’t always have symptoms. Symptoms of diabetes occur because of the high blood sugar that results in increased thirst and urination and fatigue. At a later stage when blood sugars are even higher, there is weight loss. So in a way the disease needs to progress to be clinically a problem.” Some early, mild symptoms include frequent urination, sudden weight loss, increased thirst, fatigue, and blurred vision.

But when it does become a clinical problem, the results can be shattering. Diabetes is the leading cause of blindness or visual impairment, and non-injury-related limb amputations in adults in the developed world, and is the fourth main cause of death in most developed countries. Type 2 diabetics are twice as likely to develop cardiovascular disease, and carry a higher risk of stroke, kidney failure, and dialysis.

Dr. Ramachandiran Cooppan

Prescription for change
While new drug therapies show promising results in helping to regulate the disease (properly treated, many diabetics can live to old age), preventive medicine is still the best medicine. Diabetes is a “lifestyle disease,” the prevention of which, for many, requires lifestyle changes. Proper diet, regular exercise, smoking cessation, and early diagnosis all play a critical role in preventing the disease. The American Diabetes Association recommends screening high-risk individuals, such as those from certain ethnic groups, who are obese, or have positive family histories. People with high blood pressure, or who have prior abnormal glucose tolerance should also receive regular screening.

“ It is only with early diagnosis and intervention at the stage of IGT (impaired glucose tolerance) that we will be able to start to make an impact on this disease,” said Dr. Cooppan. “We need to get the message to families and schools, to encourage better nutrition and regular physical activity to reduce the tide of obesity now crossing the nation. The best approach to type 2 diabetes is to try and prevent it in the first place.”

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