The finding surprises Jorge Calles-Escandon, MD, associate professor of endocrinology at Wake Forest University. His research team measured insulin resistance in more than 1,600 black, Hispanic, and white Americans.
"We saw that if you are an obese African-American or an obese Mexican-American, you have about the same rate of insulin resistance as an obese Anglo-American," Calles-Escandon tells WebMD. "But when we took a look at the lean group, I couldn't believe it. The lean African-American cohort -- most strikingly, the lean African-American women -- had quite a bit more insulin resistance than lean people in either of the other two groups."
Calles-Escandon's colleague, Jennifer Wolfgang, DO, presented the findings at the annual ENDO 2006 meeting of The Endocrine Society, held in Boston.
African-Americans May Have Special Diabetes Risk
Insulin resistance isn't a good thing. An essential hormone, insulin helps the cells of the body take in the sugar they need for fuel. As cells become resistant to insulin, the body struggles to compensate. The pancreas makes more insulin, but resistance increases. The end result of this vicious cycle is skyrocketing blood sugar and diabetes.
Obesity -- a body mass index (BMI) of 30 or more -- is a major risk factor for insulin resistance. But it's clearly not the only one -- especially for African-American women.
One person not surprised by these findings is S. Sethu Reddy, MD, chair of endocrinology, diabetes, and metabolism at The Cleveland Clinic.
"We already have some hint of this internationally," Reddy tells WebMD. "Asians and East Indians are much more insulin resistant at lower body mass than Europeans. In those cultures, a BMI of over 22 is considered overweight [as opposed to a BMI of 25-29.9 for Americans]. Their risk of diabetes and insulin resistance goes up at that level."
Calles-Escandon says doctors should be on the lookout for diabetes risks in African-American women, even if they aren't overweight. It would be easier if there were a simple test for insulin resistance -- but there isn't one.
"We need to find a way, in clinical practice, to set up a measure of insulin resistance that can be applied," he says. "We don't have one now."
But Reddy says such a test wouldn't necessarily change anything. Insulin resistance, he says, is part of what doctors call the metabolic syndrome. And other aspects of the metabolic syndrome -- such as high blood pressure, low levels of good HDL cholesterol, high blood fats, increased blood sugar, and abdominal obesity -- aren't hard to spot.
"So when good doctors see this constellation, they should suspect insulin resistance and treat accordingly," Reddy says. "The treatment we'd recommend for metabolic syndrome -- and for insulin resistance -- is weight management, exercise, and drugs proven in clinical trials to prevent diabetes. Insulin resistance is like the tip of the iceberg. It is a foretelling of a metabolic tsunami. We may not be prepared for it because we are so focused on the end stage of diabetes. But we don't have to wait for this end stage."