Researchers at the University of Texas Health Science Center at San Antonio and the Institute of Medical Sciences and Nutrition in Mexico City showed that grandsons and granddaughters of female rats fed an inadequate diet during pregnancy and/or lactation were more likely to become obese and insulin resistant than grandchildren of females fed an adequate diet.
The research dramatically extends previous findings that poor maternal nutrition during pregnancy and lactation predisposes the first generation of offspring to diabetes.
The study, published in the Journal of Physiology online edition on 28 April (10.1113/jphysiol.2005.086462), is the first to show that the adverse effects can be passed to adult grandchildren across two generations.
Author Dr Peter W. Nathanielsz explained: "These new findings stretch the unwanted consequences of poor nutrition across generations. It offers us important clues about the origins of insulin resistance and type 2 diabetes."
The researchers also found gender differences in the effects on the infant rats, according to the time of exposure to a poor diet during their grandmothers' own development.
"The granddaughters were more affected when their maternal grandmothers were undernourished during pregnancy. The grandsons, however, were more affected when their maternal grandmothers were undernourished during lactation."
Other researchers who have explored the issue have not tried to tease out the effects of poor nutrition in pregnancy in distinction to lactation.
Dr Nathanielsz said the finding re-emphasizes the need to provide better maternal care and advice to women about good nutrition both during pregnancy and lactation.
Incidence of diabetes is soaring around the world, linked to increasing levels of obesity and older populations. In the UK, the number of people with diabetes has surged to 1.8 million, increasing by 400,000 in the last eight years, according to charity Diabetes UK. Most of these -1.5 million - are suffering from type 2 diabetes, and a further million are likely to have the condition without being diagnosed yet.