In most present-day middle-aged populations, the risk of developing type 2 diabetes is inversely related to birth weight, according to a report in JAMA.
In other words, adults at highest risk for type 2 diabetes had the lowest birth weights, independent of potentially confounding factors such as body size and socioeconomic status in adulthood, wrote Peter H. Whincup, Ph.D., of the University of London, and his associates.
However, this association may not hold true for long. It likely reflects fetal undernutrition during the mid-20th century. The current epidemic of overweight and obesity may well reverse this association, with people who had very high birth weights eventually showing a greater propensity to develop diabetes later in life, the researchers said.
The association between low birth weight and later development of diabetes has been known since the early 1990s, but the strength and consistency of the link and its independence from confounding factors has been questioned.
Dr. Whincup and associates performed a meta-analysis of 30 studies published between 1950 and early 2008 involving 6,090 cases of diabetes among 152,084 subjects (JAMA 2008;300:2886-97). Twenty-three of the 30 showed an inverse association between birth weight and later diabetes risk, and the association was statistically significant in 9 of them. Two involved Native American populations with exceptionally high prevalences of obesity, gestational diabetes, and type 2 diabetes. In these, birth weight showed a positive, not an inverse, correlation with later diabetes risk.