WEDNESDAY, Feb. 25, 2004 (HealthDayNews) -- Children in India who were born small were more prone to develop both insulin resistance and type 2 diabetes when they became young adults.
The risk was even higher when these infants caught up with their weight gain after the age of 2, a new study says.
"None of these children really qualified for the level of obesity by the age of 12," says co-investigator Dr. K. Srinath Reddy, a professor of cardiology at the All India Institute of Medical Sciences in New Delhi. "But between the ages of about 2 and 5, there was a considerable weight gain, which brought them to what would have been considered normal but, relative to birth weight, was considered excessive."
The research appears in the Feb. 26 issue of the New England Journal of Medicine.
Obesity puts people at heightened risk for type 2 diabetes. The prevalence of these conditions is on the rise worldwide in both adults and children. Developing countries such as India are seeing a particularly rapid increase, and experts believe both environmental and genetic factors are at play.
"The last 30 years has been a time when India has experienced a tremendous amount of urbanization and a great deal of changes in the nature of the food being consumed," Reddy says. Specifically, simple carbohydrates have been replacing complex carbohydrates and fiber content has been declining while fat content (specifically saturated fats and trans fats) has been going up.
But while most everyone is experiencing the nutritional transition, only a few are at greater risk. "What's of interest here is even while the whole cohort is undergoing very similar [nutritional] changes, it is the group with the low birth weight who put on the weight from 2 years on, which is the high-risk group," Reddy continues. "The environmental factors are definitely important, but the susceptibility is particularly experienced by this group."
The current study was actually put into motion 35 years ago, in 1969, in an area of South Delhi, India. More than 20,000 married women gave birth to 8,181 babies. The length and weight of each baby was recorded within 72 hours of birth, then again at 3 months, 6 months, 9 months and 12 months, and at six-month intervals after that.
Between August 1998 and August 2002, the researchers went back and measured glucose tolerance and plasma insulin concentrations in 1,492 of those babies, now men and women aged 26 to 32.
Just over 10 percent of the group had impaired glucose tolerance, indicating a risk for diabetes, while 4.4 percent had diabetes. The people in these groups typically had a low body mass index (BMI) when they were infants followed by "early adiposity rebound," or rapid weight gain after that point.
The overall risk of developing insulin resistance or diabetes compared to babies who were not small at birth was relatively small, however. "The risk is significant, but not a huge amount," says Dr. Robert Rapaport, a professor and director of pediatric endocrinology and diabetes at Mount Sinai School of Medicine in New York City. "It's a slight increase in risk, and whether this will bear out as these children grow older remains to be seen. We need to be a little bit cautious."
Also, the researchers managed to find only a small portion (less than 20 percent) of the original group they had recorded, and the study was confined to South Delhi, which, Rapaport points out, "may or may not be representative. There are unusual forms of diabetes in India that may or may not be represented in other parts of the world."
What is striking, however, is that those who developed insulin resistance and diabetes were not actually obese, Rapaport adds.
Overall, the findings do seem to jive with previous research on the subject.
"The conventional explanation is that intrauterine malnutrition, which results in low birth weight, is also a period of metabolic programming in which the fetus in the womb learns to cope with nutritional deficiency. Otherwise, the child would be born dead," Reddy explains. "In order to survive, there is this kind of coping mechanism, which allows the fetus to survive despite low nutrient intake. That is conditioned for survival in conditions of deprivation. But when you increase nutrient availability in a fairly sudden manner, then there's a mismatch between what is programmed in utero and what they are experiencing in the environment."
There are public health messages here for both the child and the mother. One is that women need to receive adequate nutrition from the time they are girls, as this lifetime nutrition has a bearing on how much nutrition can be transferred to the baby, Reddy says.
Parents should be careful, too, about the type of nutrition their children receive in their early years. "High-calorie nutrients need to be avoided and they need to get lots of fiber and fruits and vegetables," Reddy says. "Physical activity is going to be very critical, too."