India and its neighbors Pakistan and Bangladesh are unusual cases.
Over the past 30 years, men and women there have experienced little increase in obesity. However, those countries are among ones with the biggest rise in “fasting plasma glucose,” a blood sugar measurement taken before breakfast that best reflects diabetes risk.
People in this region probably have a genetic predisposition for diabetes. At any weight above normal, they are more likely to develop the disease than many other ethnic groups. Malnutrition during a woman’s pregnancy and in a child’s first years of life — problems that still exist in some parts of the region — also appear to increase a person’s chance of developing diabetes later in life.
Overall, though, “diabetes tracks very well with economic development and urbanization,” said Hu, the Harvard researcher. Much of Africa and some other big countries, such as Indonesia, are rapidly heading that way.
In the study, each country’s diabetes prevalence and average fasting blood sugar are “age-standardized” calculations. Each country is treated as if it had the same age structure of its adult population — the same number of people age 25 to 29, the same number 30 to 34, and so on. Age standardization allows researchers to compare countries whose populations have a high percentage of old people to nations with fewer old people.
The actual number of people in the world with diabetes, however, reflects not only the underlying rate of the disease in each age group but also the size and structure of the global population today.
Between 1980 and 2008, the number of diabetics more than doubled — from 153 million to 347 million. About 30 percent of that increase came from rising prevalence of the disease in all age groups. About 30 percent came from population growth, since more people means more diabetics. About 40 percent came from the aging of the world population; diabetes is more common in older people.
Is it a consolation that “demographic factors” such as population growth and aging explain most of the increase in the number of diabetics?
“Not if you are the minister of health,” Ezzati said, and “you still have to find a way to pay for the care of the number of diabetics there are in your country.”
Ezzati and his colleagues Goodarz Danaei and Mariel M. Finucane, both of Harvard, analyzed about 370 health surveys and epidemiological studies. Fasting blood sugar was lowest in sub-Saharan Africa, parts of Southeast Asia and Andean South America. Timor-Leste (which used to be part of Indonesia), Burma, Peru, Burundi and Cambodia were the bottom five countries for men’s blood sugar in 2008.