Middle-aged adults born at the height of China’s famine in the 1950’s and 1960’s may have a greater risk of high blood sugar than those born just a few years earlier or later….
The findings support the theory that nutrition and growth during fetal development may affect the odds of developing Type 2 diabetes later in life. Previous studies have found a relationship between low birth weight and higher diabetes risk in adulthood in both developed and developing countries, said Dr. Frank B. Hu, of the Harvard School of Public Health in Boston, MA, the senior researcher on the study.
Adults born at a low weight have also been found to have higher risks of heart and kidney disease than those born within the normal range.
Dr. Hu stated that these latest findings give further support to the "developmental origins" hypothesis. According to that theory, poor nutrition during pregnancy may alter fetal development in a way that affects lifelong metabolism and disease risks.
For example, Dr. Hu said, animal research suggests that poor fetal nutrition may affect the structure and function of insulin-producing cells in the pancreas.
Dr. Hu and his colleagues looked at blood sugar levels among 7,874 Chinese adults born between 1954 and 1964. Those born between October 1, 1959, and September 30, 1961, were considered to have been exposed to the nation’s famine during fetal development. Those born earlier were categorized as exposed during early-, mid- or late-childhood; those born later were considered "unexposed."
Overall, roughly 6% of the fetal-exposed group had hyperglycemia, compared with just over 2% of the group unexposed to the famine.
Adults exposed to the famine during late-childhood also had a 6% rate of hyperglycemia. But when the researchers considered other factors — such as study participants’ age, exercise levels and smoking habits — they found that fetal exposure to the famine, especially in the regions of China most severely affected, was linked to an increased risk of hyperglycemia.
Of fetal-exposed adults from the most severely affected areas, just over 7% had hyperglycemia, versus 2% of the unexposed group, and anywhere from 2-5% of those exposed during childhood.
With other factors taken into account, adults in the group exposed during fetal development were four times more likely than their unexposed counterparts to have hyperglycemia.
What’s more, the researchers found a particularly strong link between fetal exposure to the famine and hyperglycemia among adults who currently had an "affluent" Western-style diet rather than a traditional Chinese diet. This group had the highest prevalence of hyperglycemia at 19%.
According to Dr. Hu, this suggests that a "rich" diet later in life may worsen any effects of fetal undernourishment on the long-term risk of hyperglycemia.
The researchers found no clear association, however, between famine exposure of any kind and the risk of Type 2 diabetes in adulthood. But that, they say, may be because there too few diabetes cases; at the time of the study, those in the fetal-exposed group were in their early 40’s.
Online in Diabetes July 9, 2010