Researchers have found that preterm infants are more likely to have elevated insulin levels at birth and in early childhood compared to full-term infants, findings that provide additional evidence that preterm birth may be a risk factor for type 2 diabetes, according to a study in the February 12 issue of JAMA.
In the United States, 1 in 9 live births are preterm, and l in 5 live births among African Americans are preterm. "There is growing evidence that fetal and early life events may result in permanent metabolic alterations, such as type 2 diabetes and metabolic syndrome [a combination of risk factors that increase the risk for heart disease, diabetes, and stroke]. Although available studies in children and adults support the hypothesis that preterm birth may result in adverse metabolic alterations, it is unclear whether the observed association between preterm birth, later insulin resistance, and type 2 diabetes stems from alterations in insulin metabolism during the in utero [in the uterus] period or in early childhood," according to background information in the article.
Guoying Wang, M.D., Ph.D., of the Johns Hopkins University Bloomberg School of Public Health, Baltimore, and colleagues tested the hypothesis that preterm birth is associated with elevated plasma insulin levels (indirect evidence of insulin resistance) at birth that persist into early childhood. The study included 1,358 children, born between 1998 and 2010, and followed-up from 2005 to 2012. Random plasma insulin levels were measured at birth and in early childhood.
The researchers found that plasma insulin levels were inversely associated with gestational age at birth and in early childhood. Average insulin levels at birth were 9.2 µIU/mL (micro international units per milliliter) for full term (≥ 39 weeks) and 18.9 µIU/mL for early preterm (<34 weeks) births. In early childhood, random plasma insulin levels were higher for early term, late preterm, and for early preterm both than those born full term.
"These findings provide additional evidence that preterm birth (and perhaps early term birth as well) may be a risk factor for the future development of insulin resistance and type 2 diabetes," the authors write.
In an accompanying editorial, Mark Hanson, D.Phil., F.R.C.O.G., of the University of Southampton and University Hospital Southampton, United Kingdom, writes that "the population studied by Wang et al (i.e., largely urban and minority) has a high risk of preterm birth and also of childhood obesity and later metabolic syndrome."
"The findings confirm the importance of the developmental origins of health and disease concept to such populations and raise questions about the relative effect size longer-term. However, such populations should not be viewed as special cases; they show a continuum of noncommunicable disease (NCD) risk that is initiated by a range of environmental influences operating across the normal range of early development."
"Studies such as that by Wang et al reveal just how early the first steps toward prevention of diabetes may be possible and raise the prospect that rigorous studies of early life interventions could form an important aspect of helping to reduce NCD risk."