Association between Obesity and Impaired Glucose Tolerance in New Providence Adolescents as Demonstrated by the HbA1c Test

To explore the association between obesity and the development of impaired glucose tolerance (IGT) in Bahamian adolescents. Eight hundred and seventy-three adolescents were randomly selected from five high schools in New Providence. Each student's weight, height, and waist and hip circumferences were recorded to determine body mass index (BMI). Individuals with BMIs above the 84th and 95th percentiles were classified as overweight and obese, respectively. Venous blood samples were collected from each subject and haemoglobin A1c (HbA1c) levels were measured using a direct immunoassay method. The criterion established by the International Expert Committee for the diagnosis of IGT (HbA1c concentration of 6.0-6.4%) was used. An analysis of covariance was performed to evaluate the relationship between obesity and IGT, and a logistic regression analysis predicted the risk of IGT based on BMI classification. Of the 861 adolescents who completed the study, 15.0% were classified as overweight, 15.2% as obese and 7.9% as severely obese. The overall cumulative prevalence of IGT based on HbA1c levels was 16 100 cases per 100 000 adolescents and was greater in males than in females. Higher percentages of overweight and obese students were identified as having IGT compared with their normal-weight counterparts. An analysis of covariance with post hoc analyses revealed that severely obese males and females, respectively were almost 26 (OR = 25.54, 95% CI 9.92, 65.77) or 23 (OR = 22.96,95% CI 9.81, 53.73) times more likely to develop IGT than their normal-weight counterparts (p < 0.05). The data show a strong positive association between IGT and obesity among Bahamian adolescents.