Determinants of High Fasting Insulin and Insulin Resistance Among Overweight/Obese Adolescents (original) (raw)

Hyperinsulinaemia is the earliest subclinical metabolic abnormality, which precedes insulin resistance in obese children. An investigation was conducted on the potential predictors of fasting insulin and insulin resistance among overweight/obese adolescents in a developing Asian country. A total of 173 overweight/obese (BMI > 85 th percentile) multi-ethnic Malaysian adolescents aged 13 were recruited from 23 randomly selected schools in this cross-sectional study. Waist circumference (WC), body fat percentage (BF%), physical fitness score (PFS), fasting glucose and fasting insulin were measured. Insulin resistance was calculated using homeostasis model assessment of insulin resistance (HOMA-IR). Adjusted stepwise multiple regression analysis was performed to predict fasting insulin and HOMA-IR. Covariates included pubertal stage, socioeconomic status, nutritional and physical activity scores. One-third of our adolescents were insulin resistant, with girls having significantly higher fasting insulin and HOMA-IR than boys. Gender, pubertal stage, BMI, WC and BF% had significant, positive moderate correlations with fasting insulin and HOMA-IR while PFS was inversely correlated (p < 0.05). Fasting insulin was primarily predicted by gender-girls (Beta = 0.305, p < 0.0001), higher BMI (Beta = −0.254, p = 0.02) and greater WC (Beta = 0.242, p = 0.03). This study demonstrated that gender, BMI and WC are simple predictors of fasting insulin and insulin resistance in overweight/obese adolescents. An abnormally high insulin level or hyperinsulinaemia has been hypothesised as the earliest physiological risk marker of cardiovascular and metabolic diseases in obese children 1. In obese children, hyperinsulinaemia can initially compensate well for insulin resistance 2. However, chronic obesity may persistently impair insulin-mediated glucose metabolism 3. Consequently, insulin resistance occurs as a response of the body to chronic hyperinsulinaemia 4 , resulting in glucose dysregulation 1. The gold standard to measure insulin resistance is via the euglycaemic insulin clamp, which is a complicated and clinically impractical procedure as it requires three hours of continuous administration of both insulin and glucose intravenously 5. Thus, in clinical practice, the evaluation of hyperinsulinaemia by measuring fasting plasma insulin may, therefore, provide a rational clinical alternative for evaluating insulin resistance 5. Several models have incorporated fasting plasma insulin to indirectly measure insulin resistance, including a homeostasis model assessment of insulin resistance (HOMA-IR), a quantitative insulin sensitivity check index (QUICKI) and the fasting glucose/insulin ratio (FGIR). In children and adolescents, HOMA-IR has been shown to be more reliable than FGIR and QUICKI 6 and has been used as a measure of insulin resistance in this population. Similar to other countries worldwide, Malaysia, a multi-ethnic country in Southeast Asia is experiencing an increase in childhood obesity. In Malaysia, the 4 th National Health and Morbidity Survey 2011 reported a 6.1% prevalence of obesity among Malaysian children under 18 years of age, with higher rates occurring in urban