title: High-risk glycated hemoglobin trajectories established by mid-20s: findings from a birth cohort study.
abstract: OBJECTIVE
  To describe the natural history of glycemia (as measured by glycated hemoglobin (HbA1c)) over 12 years using group-based trajectory modeling (GBTM), and to examine baseline predictors of trajectory.
  
  
  METHODS
  HbA1c data collected at ages 26, 32 and 38 in the long-running, prospective Dunedin Multidisciplinary Health and Development Study were used to assign study members (n=893) to trajectories applying GBTM. A generalization of the model allowed the statistical linking of baseline demographic, smoking and anthropometric characteristics to group membership probability.
  
  
  RESULTS
  Mean HbA1c increased with age, as did prevalence of prediabetes, diabetes and dysglycemia. The greatest increase occurred between ages 26 and 32. Glycemic health status at age 26 predicted glycemic health status at age 38. 3 HbA1c trajectory groups were identified: 'low' (n=98, 11.0%); 'medium' (n=482, 54.0%); and 'high' (n=313, 35.0%) with mean HbA1c of 29.6, 34.1, and 38.7 mmol/mol, respectively, at age 38. High waist circumference (≥880 mm for women and ≥1020 mm for men), high waist-height ratio (≥0.50), and being a smoker at age 26 predicted membership of the least favorable trajectory over the next 12 years. High body mass index (≥30) at age 26 did not predict of trajectory.
  
  
  CONCLUSIONS
  Trajectories of HbA1c are established relatively early in adulthood. HbA1c levels, waist circumference, waist-height ratio, and smoking status at age 26 are valid clinical predictors for future dysglycemic risk. The identification of HbA1c trajectories and their predictors introduces the possibility of an individualized approach to prevention at an earlier stage than is currently done.
authors.affiliation: Faculty of Dentistry, Department of Oral Sciences , University of Otago , Dunedin , New Zealand.
authors.forename: Dara M
authors.initials: DM
authors.lastname: Shearer
authors.affiliation: Faculty of Dentistry, Department of Oral Sciences , University of Otago , Dunedin , New Zealand.
authors.forename: W Murray
authors.initials: WM
authors.lastname: Thomson
authors.affiliation: Faculty of Dentistry, Department of Oral Rehabilitation , University of Otago , Dunedin , New Zealand.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Broadbent
authors.affiliation: Department of Human Nutrition, University of Otago, Dunedin, New Zealand; Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand; Edgar National Centre for Diabetes and Obesity Research, Dunedin, New Zealand.
authors.forename: Rachael
authors.initials: R
authors.lastname: McLean
authors.affiliation: Dunedin Multidisciplinary Health and Development Research Unit , University of Otago , Dunedin , New Zealand.
authors.forename: Richie
authors.initials: R
authors.lastname: Poulton
authors.affiliation: Department of Human Nutrition, University of Otago, Dunedin, New Zealand; Edgar National Centre for Diabetes and Obesity Research, Dunedin, New Zealand.
authors.forename: Jim
authors.initials: J
authors.lastname: Mann
keywords: BMI; HbA1c; Smoking; Waist Circumference