Diabetes Types

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Risk Associated with Weight and BMI

The Surgeon General estimates that 61 percent of U.S. adults are overweight, as are 13 percent of children and adolescents. Obesity has been on a steady rise over the past few decades, with nearly one third of all adults over age twenty classified as obese, according to the 1999-2000 National Health and Nutrition Examination Survey (NHANES). Being overweight or obese is a primary risk factor for developing prediabetes and type 2 diabetes. The U.S. Department of Health and Human Services (HHS) reports that over 80 percent of people with type 2 diabetes are clinically overweight.

Why Is Weight a Risk Factor?

Too much fat makes it difficult for the body to use its own insulin to process blood glucose and bring it down to normal circulating levels. Why? There are three reasons:

  • Overweight people have fewer available insulin receptors. When compared to muscle cells, fat cells have fewer insulin receptors, the place where the insulin binds with the cell and "unlocks" it to process glucose into energy.
  • More fat requires more insulin. The pancreas starts producing larger and larger quantities of insulin in order to "feed" body mass, and consequently insulin resistance turns into a catch  22. Excess blood sugar must be stored as fat, and excess fat promotes further insulin resistance.
  • Fat cells release free fatty acids (FFAs). Fat cells and tissue, particularly abdominal fat, release free fatty acids, which interfere with glucose metabolism.

Leptin, a hormone in fat cells that helps to metabolize fatty acids, has provided an important clue to the relationship between obesity and type 2 diabetes. Discovered by Rockefeller University researchers in 1995, leptin also plays a part in sending a satiety or "all full" signal to the brain to stop eating when body fat increases, and an "empty" signal when body fat is insufficient. It appears that a type of leptin resistance may lead to a situation where fatty acids are deposited instead of metabolized, leading to eventual insulin resistance.

Your BMI

Obesity and body fat are measured by body mass index (BMI) a number that expresses weight in relationship to height and is a reliable indicator of overall body fat. People with a BMI of 25 to 29.9 are considered overweight; those with a BMI of 30 or over are obese. Extreme obesity is classified as a BMI of 40 or higher. The NIDDK (National Institute of Diabetes & Digestive & Kidney Diseases) reports that 67 percent of people with type 2 diabetes have a BMI of 27 or higher and 46 percent have a BMI of 30 or higher. You should aim for a BMI of 18.5 to 24.9, which is considered normal. BMI for children and young adults ages two to twenty is calculated differently. A charting system called BMI for age compares each child's weight in relation to other children of the same age and gender on a growth chart in terms of percentiles. For example, a girl in the thirtieth percentile would weigh the same or more than 30 percent of girls the same age.

E Alert

You know smoking is bad for your health, but did you also know it can increase your diabetes risk? Smoking constricts blood vessels, raising blood pressure and increasing the risk of coronary artery disease. It also stimulates the release of catecholamines, which have been shown to promote insulin resistance. A BMI for age that is equal to or over the ninety fifth percentile is considered overweight, while the eighty fifth to ninety fourth percentile is "at risk" for being overweight. Growth charts used for assessing pediatric BMI or age are based on National Health and Nutrition Examination Survey (NHANES) data and generated by the U.S. Centers for Disease Control (CDC). The CDC Web site has more information.

Body Shape

Having an apple shaped body, with excess pounds packed in the midsection rather than the hips, is another hallmark of insulin resistance. In fact, the National Institutes of Health recommends that waist circumference be used as a screening tool for evaluating the risk of heart disease and type 2 diabetes. Another type 2 risk sometimes related to weight is an inactive lifestyle. Exercise, even at a moderate level, reduces blood glucose levels. People who lead sedentary lifestyles, exercising less than three times a week, are more likely to develop type 2 diabetes than those who get up and move on a regular basis.