Answer to Map #47

Click here for a full-size version of this week’s map.

Back to this week’s maps and hints.

Answer: This week’s map was a choropleth in which each county of the United States was shaded in proportion to the percentage of its population that suffers from diabetes.

Overall, about 9.3% of Americans have diabetes. Between 90% and 95% of the total number of diabetes cases are type 2 diabetes, an acquired form of the disease that is associated with obesity and lack of exercise.

That means that a map of diabetes rates inevitably has a lot in common with a map of obesity rates. Indeed, the state where diabetes is most prevalent is Mississippi (11.3%), which is also one of the states with the highest obesity rates. Colorado, one of the states with the lowest obesity rates, is also one of the states with the lowest diabetes rates. (Obesity rates, it should be said, are tough to measure because people have different definitions for what constitutes obesity, plus estimates are often based on self-reported surveys)

So how can you tell a diabetes choropleth from an obesity choropleth? The simplest way is to look at Alaska. Alaska has a fairly high obesity rate, but a relatively low diabetes rate. One interesting reason for this disparity is that Alaska Natives have the lowest diabetes rates of any race in the United States (5.5%).

Susceptibility to diabetes is not fully understood, but there is definitely a genetic component to it. This genetic predisposition is exacerbated by poverty and unequal access to good nutrition. Consequently, there are significant differences in diabetes rates among different races. Only 7.1% of non-Hispanic whites have diabetes, but 12.6% of African-Americans do. That’s a big difference.

Which race has the highest rates of diabetes? That would be Native Americans, of whom 33%—fully one third of adults—suffer from the disease. On our choropleth, this high incidence is particularly visible in southwestern South Dakota, where you see some extremely bright counties that coincide with some extremely impoverished areas home to large Native American populations. (Try looking at this week’s map, week 15’s map of child poverty, and week 13’s map of Native American populations side by side)

The worst extended area for diabetes, however, is in the South. The Centers for Disease Control and Prevention have identified a so-called “Diabetes Belt” covering 644 counties in 15 states. The idea is that the “belt” covers every county with a rate of at least 11% that is near other counties with that rate. Every single county in Mississippi is part of this belt.

Next map: Click here to try out our newest map question.