Adolescent Body Mass Index (BMI) can predict early occurence of diabetes and heart disease in adulthood

New England Journal of Medicine Study Shows that BMI at Adolescence in the Normal Range Can Nevertheless Predict Risk of Early Type 2 Diabetes and Heart Disease in a Differential Manner

18-Apr-2011 - Israel

A large cohort study following 37,000 teenagers for 17 years found that while diabetes risk is mainly associated with increased Body Mass Index close to diagnosis in adulthood (age 30-45 years), elevated BMI at adolescence and at adulthood are independently of each other associated with the risk of coronary heart disease.

The study, published in the New England Journal of Medicine, assessed the occurrence of both diseases in young adulthood, an age group that has been rarely studied, but has experienced an increase in the incidence of these diseases in recent decades.

The joint research team was lead by Dr. Amir Tirosh (Sheba Tel-Hashomer's Talpiot program and Brigham and Women’s Hospital and Harvard Medical School's) researchers Dr. Iris Shai and Dr. Assaf Rudich, from Ben-Gurion University of the Negev. With additional researchers from the Israeli Defense Forces (IDF) Medical Corps and Tel Hashomer Hospital, the team followed IDF career personnel beginning at age 17.

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The IDF recorded BMI of personnel (BMI, the weight in kilograms divided by the squared height in meters) at baseline and again every few years. During a mean follow-up period of 17 years, the average BMI of the participants rose at a rate of 0.2-0.3 units per year, rising to an average weight gain of approximately 15 Kg. (~30 lbs) between ages 17 and 30. The researchers were able to control for multiple risk factors for both diseases, including age, fasting blood glucose, blood lipids, blood pressure, smoking, exercise habits and family history.

The researchers found that it was possible to predict the increased risk for developing both diabetes and coronary heart disease even if the BMI was within the normal range (<25 Kg/m2). A BMI of 25 or more is considered overweight while 30 BMI or higher is considered obese.

According to the study, every rise in one unit of BMI was associated with ~10 percent increased risk for type 2 diabetes in early adulthood, and a 12 percent increase in the risk for heart disease. Remarkably, this elevated risk was significant at a BMI at age 17 of 23.4 Kg/m2 or higher for diabetes and 20.9 Kg/m2 or higher for heart disease. For diabetes, BMI at age 17 predicted the risk mainly since it associated with BMI later in life. However, for heart disease, both BMI at adolescence as well as BMI at adulthood independently of each other predicted the risk of the disease. During the 17 year study period, 1,173 new cases of diabetes and 327 new cases of heart disease were diagnosed.

According to Dr. Tirosh, "Our results suggest that the obesity problem in children and teens is likely just the tip of an iceberg for increased risk for the occurrence of type 2 diabetes and heart disease in your 30's and 40's. While this is an observational study, it does suggest that an adolescent with a relatively high BMI, who grows up to become a lean adult, practically eliminated the added risk of developing diabetes attributed to his BMI at adolescence. Conversely, the risk of that person for heart disease will remain elevated compared to the lean teen who became a lean adult, though still will be lower than that of the heavier teen who became an obese adult. Therefore, for effective prevention of early occurrence of heart disease in adulthood, very early intervention to promote healthy life-style habits seems essential, even during childhood."

Prof. Iris Shai of BGU’s Department of Epidemiology, Faculty of Health Sciences (FOHS), explains: "Heart disease appears to have a longer "memory" for BMI than diabetes, so the history of a person's BMI should be part of medical risk assessment. We have options, not necessarily pharmacological, to offer patients to decrease their risk for heart disease.”