Epidemiologia da hemoglobina glicada (HBA1C) em duas coortes de nascimentos - Pelotas/RS

Abstract

Glycated haemoglobin (HbA1c) is the best index for long-term glucose control in diabetic patients and a screening tool for detecting diabetes in general population. The HbA1c measurement offers some advantages compared with other glycemic indicators. It can be performed at any time of the day, irrespective of fasting or feeding, and it is relatively cheap. In epidemiological studies, HbA1c has been found to be associated with the incidence of diabetes and cardiovascular diseases (CVD), and all-cause mortality in populations free of disease. Therefore, HbA1c is used to examine the disease risk associated to hyperglycaemia in healthy populations. This thesis aimed to describe the epidemiology of HbA1c (distribution and associated factors) and to evaluate the association of growth patterns with cardiometabolic risk markers in adolescents and young adults. A better understanding of the these relations may help to identify groups of the population with increased risk of cardiometabolic diseases. The thesis includes three papers. In the first paper, we systematically reviewed literature assessing the relationship between growth (change in weight, height or BMI) during infancy, childhood and adolescence and indicators of glucose and insulin metabolism in adulthood (fasting glycemia, 2 hours glycemia after an Oral Glucose Tolerance Test, hyperglycemia, HOMA-IR). Some inconsistencies in growth definitions and age intervals were identified. The most consistent evidence was documented for rapid weight or body mass index (BMI) gain from childhood onwards and a worse glucose and insulin metabolism profile at adult age. In the second paper, we described the distribution of HbA1c levels in 18 and 30 years old individuals according to early-life and contemporary factors in the 1993 and 1982 Pelotas Birth Cohorts. The distribution of the HbA1c was approximately normal. HbA1c mean levels were significantly higher in individuals self-reported as black/brown skin color compared to those self-reported as white in both cohorts. Parental history of diabetes was associated with higher HbA1c mean in adults, while stunting at one year old presented an inverse relation with the outcome in adolescents. No other early and contemporary factors were associated with HbA1c levels in adults or adolescents. In the third paper, we evaluated the effect of growth trajectories (linear growth and relative weight gain) from birth to adolescence on cardiometabolic risk markers levels at age 18 years in the 1993 Pelotas Birth Cohort. The outcomes were random glucose, HbA1c, Creactive protein, total cholesterol, LDL-C, HDL-C, triglycerides, systolic and diastolic blood pressure, BMI and waist circumference. Our study showed that rapid weight gain from childhood onwards is positively associated with several markers of cardiometabolic risk in adolescents. Evidence on linear growth needs further analyses. Overall, our results suggest that prevention of excessive weight gain after the two first postnatal years might be important in reducing cardiometabolic risk later in life.