Originally Published Sept  2007

 

WHO GETS TYPE ll DIABETES?

Diabetes type ll affects at least 17 million Americans, and the incidence is sharply rising. A major 2000 US study reported that the prevalence of type ll diabetes increased by one-third between 1990 and 1998 and the biggest increase (70%) was among young adults in their 30s. Type ll diabetes typically has developed after the age of 40. In 1999 alone it rose by 6% overall with an increase of 10% in African Americans. The primary reason for this dramatic increase appears to be the parallel increase in obesity. And as more and more cultures adopt Western dietary habits, it is likely that diabetes type ll will reach epidemic proportions throughout the world.

DIABETES IN CHILDREN AND ADOLESCENTS

Until recently, diabetes in children was almost always type 1 (an autoimmune disease). Of major concern, however, are estimates that between 8% and 45% of new diabetes cases in children are type ll. (The significant differences in estimates are due to the difficulties in detecting the disease in children.) It is evident that diabetes is on the increase, not only in the US but also in other nations, including Europe and Japan. Diabetes is usually recognized in children who are in middle to late puberty. It most often occurs in girls and children who are overweight.

LOW BIRTH WEIGHT

Research now indicates that low birth weight is a risk factor for type ll diabetes. Some research indicates that malnutrition in the pregnant woman may be responsible for causing metabolic abnormalities in the developing fetus that eventually lead to diabetes.

OBESITY

In a 2001 study of nearly 85,000 nurses, obesity was the number one risk factor for diabetes type ll. It is estimated that 80% to 95% of the current dramatic increases in type ll diabetes is due to obesity and having excess fat in the abdominal region. Excess body fat appears to play a strong role in insulin resistance, but the way the fat is distributed is also significant. Weight concentrated around the abdomen and in the upper part of the body (apple-shaped) is associated with insulin resistance and diabetes, heart disease, high blood pressure, stroke, and unhealthy cholesterol levels. Fat that settles in a "pear-shape" around the hips and flank appears to have a lower association with these conditions. One study suggested that waist circumferences greater than 35 inches in women and 40 inches in men signify increased risk for heart disease and diabetes.

Of note, however, obesity does not explain all cases of diabetes type ll, which is also common among people in countries where weights tend to be low, such as Asia or India.

FAMILY HISTORY

Between 25% to 33% of all type ll patients have family members with diabetes. Having a first-degree relative with the disease poses a 40% risk of developing diabetes. One study reported that people with positive family histories have a higher risk for developing the disease at an earlier stage with more severe features.

Because families share many lifestyle features (eating and exercise habits) it is difficult to determine when genetics or environment play the major role. When clusters of diabetes type 1 and ll appear within families, genetic factors should be strongly suspected. Interestingly, one study reported that type ll patients who had relatives with type 1 and type 2 diabetes tended to need insulin therapy but also had lower risks for heart disease than patients with only a type ll family history.

ETHNICITY

The risk for type ll diabetes varies among population groups. Diabetes also seems to pose higher or lower risks for specific complications among ethnic groups. Genetic, socioeconomic factors, or both seem to be involved in ethnic differences.

African Americans. A 2000 study reported that African American men have one and a half times the risk of developing type ll diabetes and African American women have twice the risk as their Caucasian peers. An earlier 1999 study also found that African Americans with diabetes are also at higher risk for amputations than diabetic Caucasians, which is most likely due to a higher incidence of high blood pressure and smoking as well as poorer health care. Genetic factors also play a role. For example, there is some evidence that African Americans have insulin abnormalities unrelated to dietary or other factors.

Native Americans. The Pima tribe in Arizona has an incidence of type ll diabetes that is 19 times higher than that of the white population. The risk for diabetic complications among young Pima adults is also very high. Other Native American tribes in North America are also at high risk for type ll diabetes. The association between diet and diabetes among this population remains critical, however, in assessing these ethnic differences. In one study, Pimas who lived in Mexico exercised more and ate less fat (but consumed more calories) than Pima tribes in Arizona. The incidence of diabetes in their Arizona Pima relatives was about 50%, while it was only 6% in the Mexican Pima tribes (about the same as their non-Pima neighbors).

Hispanic Americans. The rate of type ll diabetes is also very high among Mexican Americans, approximately double that for Caucasians.

Maturity-Onset Diabetes in Caucasian Youth. Maturity-onset diabetes in youth (MODY) is a rare genetic form of type ll diabetes that develops only in Caucasian teenagers. It accounts for 2% to 5% of type ll cases. (It should be noted that this is not the diabetes associated with obesity that is now being seen increasingly in young people, including Caucasians.)
DIABETES IN THE PREGNANT WOMAN (GESTATIONAL DIABETES)

An estimated 5% of pregnant women develop a form of type ll diabetes, usually temporary, in their third trimester called gestational diabetes.