Low Vitamin B12 Levels and Its Association With Insulin Resistance: A Potent Cardiovascular Risk Indicator in Childhood Asthma.

Abstract

Introduction As insulin resistance metabolically affects the body mass index (BMI), obese asthma children have more severe diseases than children with normal body mass index. A low level of vitamin B12 (Vit B12) is a known atherogenic factor by increasing the homocysteine level and therefore promotes cardiovascular morbidity and mortality. Limited studies have evaluated the role of serum B12 and insulin resistance among poorly controlled asthma in children. The purpose of the study was to compare the cardio-metabolic risk factor such as BMI, waist-hip ratio (WHR), insulin resistance, and vitamin B12 in well-controlled and poorly-controlled asthma patients and to determine the relationship between these parameters with the severity of asthma as assessed by Pulmonary Function Test. Methodology Based on the asthma control questionnaire and Global Initiative for Asthma (GINA) criteria, chronic asthma patients (n=60) of age 10-15 years were divided into two groups, namely well-controlled and poorly-controlled (30 each). Anthropometry was assessed by BMI and waist-hip ratio, and fasting blood samples were collected for the estimation of blood glucose, insulin, and serum vitamin B12 levels. Insulin resistance (HOMA-IR) was calculated using the formula- fasting glucose (mg/dL) x fasting insulin (µIU/mL)]/405. Forced expiratory volume (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio were measured to assess the pulmonary function test. Results There were significant differences in the values of the BMI, insulin resistance, vitamin B12, and pulmonary function tests between poorly controlled and well-controlled asthma (p<0.01). The FEV1: FVC% was negatively correlated with BMI (r=0.53), WHR (r=0.50), glucose (r=0.68), insulin (r=0.68), Insulin resistance (r=0.80),and positive correlation with Vit B12 (0.73). In addition, Vit B12 and HOMA-IR correlatenegatively (r=0.76). Conclusion This study concludes that the level of Vit B12 is decreased and insulin resistance is increased in poorly controlled asthmatic children in comparison to well-controlled asthma. These factors along with the increased BMI in poorly controlled asthma can predispose to cardiometabolic risk which needs attention.