The Basics: Diabetes and Prediabetes and Why They Are on the Rise - 8

Under Beating Diabetes

How Our Lifestyle Has Made Us Vulnerable to Diabetes

In 1985, an estimated 30 million cases of diabetes existed worldwide. This number increased to 177 million in 2000 and is estimated to rise to at least 370 million by 2030, almost all from type 2 diabetes associated with aging, obesity, and inactivity. In the United States, the numbers of cases of diabetes and obesity have risen in parallel. Diabetes and prediabetes affect IS million and almost 40 million persons, respectively, and the metabolic syndrome affects almost 25 percent of the U.S. population.

It is all too easy to ascribe these alarming statistics to the increased numbers of the very obese and the very old. But only about 2.3 percent of the population is severely obese and only 3.3 percent of the population is older than eighty-small percentages. The major public health problem is not caused by very large or very old people. Most cases of diabetes and prediabetes are caused by the ever-increasing population that is overweight or only modestly obese. The fraction of the U.S. population in 2000 that was overweight (defined as a body mass index, or BMI, between 25 and 30) increased to almost 35 percent, and the fraction that was obese (BMI of 30 or greater) increased from 13 percent in 1960 to almost 31 percent in 2000. (See sidebar on measuring your BMI.) Thus, the fraction of the U.S. population that is either overweight or obese has risen to an astounding 65 percent.

Are You a Healthy Weight? Measuring Your BMI

Body mass index, or BMI, is a convenient measure of whether your weight is appropriate for your height. Because taller people will weigh more than shorter people, the calculation takes your weight (in kilograms), divides it by your height (in meters squared), and comes up with a measure in kg/m2. The calculation can also be performed if you know your weight and height only in pounds and feet and inches, respectively (see Table 1.4).

The BMI provides a measure of weight for height; it does not provide a direct measure of obesity, meaning who has excess body fat. Nevertheless, for the vast majority of people, a high BMI (between 25 and 30 is defined as being overweight, and 30 or above is considered obese) is synonymous with having too much body fat. Rarely, bodybuilders and other trained athletes may have "excess" weight and a high BMI that is composed not of fat but of muscle. For most of us, this is not the case.

Estimating Your Body Mass Index (BMI)

You can use Table 1.4 to estimate your body mass index. First, select your weight (to the nearest ten pounds) in one of the columns across the top. Then move your finger down the column until you come to the row that represents your height. Inside the square where your weight and height meet is a number that is an estimateof your BMI. For example, if you weigh 160 pounds and are five feet seven inches, your BMI is 25.


Industrialized Society Disease in the "Third World"

The changes in lifestyle in North America and Europe have occurred slowly over centuries, but today we can see those changes as in time-lapse "photography." Take for example the island of Nauru, in the Central Pacific. Until the 1950s, Nauru island lifestyle consisted of very limited subsistence farming as well as fishing. Diets were largely composed of fish, island vegetables, and plantains. The people were largely cut off from the outside world, and there was little in the way of industry.

Around 1960, investors recognized that Nauru's phosphate-rich soil held great financial potential as fertilizer. By 1976, the small population of Nauru was one of the wealthiest in the world. The toil of farming and fishing disappeared in a single generation. Motorbikes and cars replaced walking as the common mode of transportation, imported food was sold in the grocery stores, and electric appliances and televisions became commonplace.

The impact of this sudden and dramatic change in the lifestyle of the citizens of Nauru was profound. Before industrialization, obesity and diabetes were virtually unknown; however, by 1976, the average Nauruan was obese. The obesity and inactivity were a potent combination: 34.4 percent of the population had developed diabetes.

Source: David M. Nathan, M.D. and Linda M. Delahanty, M.S., R.D, Beating Diabetes: The First Complete Program Clinically Proven to Dramatically Improve Your Glucose Tolerance, The McGraw-Hill Companies, Inc. (2005)