Elderly twins, whether identical or fraternal, seem to have a higher risk of developing type 2 diabetes - suggesting, researchers say, that certain prenatal factors may contribute to the disease even late in life.

In a study comparing older same-sex twins with other older adults, Danish researchers found that the twins had a higher rate of abdominal obesity and problems with blood-sugar metabolism.

They also had nearly three times the prevalence of type 2 diabetes, as well as a 60 percent higher risk of developing the disease over the next 10 years, the researchers report in the journal Diabetes.

What’s more, the findings were similar among identical and fraternal twins: roughly 16 percent of fraternal twins and 17 percent of identical twins had type 2 diabetes at the outset, compared with less than 6 percent of adults who’d been born singletons.

And when one fraternal twin had the disorder, the chances of the other developing it by the age of 84 were about 70 percent - on par with the odds among identical twins, and much higher than the 35-percent odds other research has found among siblings.

Because fraternal twins share no more genes than non-twin siblings do, the results suggest that something about the fetal environment - rather than genetics - may cause the higher diabetes prevalence among twins, according to the researchers.

Twins have a “different and more adverse fetal environment as compared to singletons,” which may help explain the increased type 2 diabetes risk, noted lead researcher Pernille Poulsen, of the Steno Diabetes Center in Gentofte, Denmark.

For example, she told Reuters Health, there is a well-known association between low birthweight and higher diabetes risk later in life.

Low birthweight has been linked to other adulthood health conditions, such as high blood pressure. Researchers speculate that low birthweight and related factors - including inadequate nutrition and restricted growth in the womb - may “program” the developing metabolic system in a way that makes it ultimately more vulnerable to disorders like diabetes.

Poulsen said that it is unclear exactly which prenatal factors may be key to later diabetes risk - whether it’s an expectant mother’s diet, for instance, or pregnancy-related health problems, like anemia or high blood pressure.

It’s also possible, Poulsen noted, that factors early in life - such as rapid “catch-up” growth in low-birthweight infants - play some role in diabetes development later on.

SOURCE: Diabetes, June 2009.