Risk factors such as insulin resistance and high blood pressure begin as early as age 15, according to a recent study.
Researchers measured obesity, insulin resistance, blood pressure and cholesterol levels of 267 boys and girls. Measurements were taken when the young people were 13 and again when they were 15. Obesity levels were measured using a body mass index (BMI) calculation. BMI is the person's weight in kilograms divided by their height in meters squared (wt/ht2). Researchers classified those with a BMI of 25 or greater as overweight while those with a BMI of 30 or greater were considered obese. Cholesterol and triglycerides were measured with a total cholesterol blood test, including levels of HDL (good) cholesterol, LDL (bad) cholesterol and triglycerides.
Insulin resistance was measured through a process called an insulin clamp study. Participants were given a steady infusion on insulin through an IV, along with enough glucose to maintain safe body levels. The dose of the insulin was "clamped," meaning that it was held at a certain amount. Researchers then measured the amount of glucose needed. Lower amounts of glucose processed by the body indicated insulin resistance.
At the time of the second measurements, researchers found a significant correlation between insulin resistance and systolic blood pressure in the boys. Systolic blood pressure is the top number in a blood pressure reading. This measurement represents the highest level of the blood's pressure within the artery walls and corresponds to the contraction of the heart's main pumping chambers (ventricles). Higher insulin resistance was related to a higher systolic blood pressure in the the15-year-old boys.
Researchers also found that insulin resistance in adolescents was linked to a decrease of "good" HDL cholesterol and an increase of triglycerides. In addition, the correlation between high blood pressure and insulin resistance was directly affected by levels of obesity.