Risk for Diabetes Tied to Degree and Duration of Obesity

Emma Hitt, PhD

September 13, 2011

September 13, 2011 — Degree and duration of obesity, expressed as excess body mass index (BMI)-years, shows a better correlation with the risk of developing type 2 diabetes compared with BMI alone, according to a new study.

Joyce M. Lee, MD, MPH, from the Division of Pediatric Endocrinology at the University of Michigan, Ann Arbor, and colleagues reported their findings online September 5 in the Archives of Pediatrics and Adolescent Medicine.

The current study includes data from the National Longitudinal Survey of Youth 1979, a nationwide study following participants (14 - 21 years old) during a 25-year period starting in 1981.

The study included 8157 young adults with an average age of close to 20 years. Participants periodically provided information on self-determined height and weight and self-reported the onset of diabetes, based on clinical diagnosis of the disease. The month and year of the diagnosis was included, but information on diabetes type was not, and medical verification of the diabetes was not available.

Participants reporting normal weight (BMI < 25 kg/m2) the year before diabetes diagnosis were excluded from the analysis to account for possible cases of type 1 diabetes, leaving 337 participants who reported developing diabetes, presumed to be type 2, with a median age of onset of 37.2 years. The researchers assessed the correlation between excess BMI-years, a measure of the extent and duration of obesity, and incident diabetes.

They found that the relationship between excess BMI-years and risk of developing diabetes depended on age, with younger individuals showing a higher risk of developing diabetes when the excess BMI-years value was higher vs lower.

In addition, higher levels of excess BMI-years correlated with a greater risk of developing type 2 diabetes, regardless of age. For example, 40-year-old white men with 200 cumulative excess BMI-years vs a similar cohort with 100 excess BMI-years had a 2.94 times higher odds of developing diabetes (95% confidence interval, 2.36 - 3.67).

The combination of race and excess BMI-years also correlated with incident diabetes. Hispanic participants with excess BMI-years in the range from 0 to 200 had a higher risk of developing diabetes when compared with black individuals. White participants within the same excess BMI-years range had the lowest risk. However, the risk of developing diabetes was similar for all races at higher levels of excess BMI-years, from 300 to 500.

Study limitations include the use of self-reported data without specification of diabetes type.

"[E]xcess BMI-years were associated with self-reported incident diabetes, and this risk was higher for younger adults and possibly for black and Hispanic adults compared with white adults at a given level of excess BMI-years," Dr. Lee and colleagues conclude.

According to the researchers, "[f]uture public health interventions focused on diabetes prevention may need to target younger nonwhite individuals to prevent a further acceleration in diabetes rates."

Dr. Lee's work is supported by grants from the National Institute of Diabetes and Digestive and Kidney Diseases, and from the Clinical Sciences Scholars Program at the University of Michigan. The other authors have disclosed no relevant financial relationships.

Arch Pediatr Adolesc Med. Published online September 5, 2011. Abstract


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