title: Geographical variation in the progression of type 2 diabetes in Peru: The CRONICAS Cohort Study.
abstract: BACKGROUND
  The study aims were to estimate the incidence and risk factors for T2D in four settings with different degree of urbanization and altitude in Peru.
  
  
  METHODS
  Prospective cohort study conducted in urban, semi-urban, and rural areas in Peru. An age- and sex-stratified random sample of participants was taken from the most updated census. T2D was defined as fasting blood glucose ⩾7.0mmol/L or taking anti-diabetes medication. Exposures were divided into two groups: geographical variables (urbanization and altitude), and modifiable risk factors. Incidence, relative risks (RR), 95% confidence intervals (95%CI), and population attributable fractions (PAF) were estimated.
  
  
  RESULTS
  Data from 3135 participants, 48.8% males, mean age 55.6years, was analyzed. Overall baseline prevalence of T2D was 7.1% (95%CI 6.2-8.0%). At follow-up, including 6207 person-years of follow-up, a total of 121 new T2D cases were accrued, equating to an incidence of 1.95 (95%CI 1.63-2.33) per 100 person-years. There was no urban to rural gradient in the T2D incidence; however, compared to sea level sites, participants living in high altitude had a higher incidence of diabetes (RR=1.58; 95%CI 1.01-2.48). Obesity had the highest attributable risk for developing T2D, although results varied by setting, ranging from 14% to 80% depending on urbanization and altitude.
  
  
  CONCLUSIONS
  Our results suggest that the incidence of T2D was greater in high altitude sites. New cases of diabetes were largely attributed to obesity, but with substantial variation in the contribution of obesity depending on the environment. These findings can inform appropriate context-specific strategies to reduce the incidence of diabetes.
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru; Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Antonio
authors.initials: A
authors.lastname: Bernabé-Ortiz
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Rodrigo M
authors.initials: RM
authors.lastname: Carrillo-Larco
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru; Program in Global Disease Epidemiology and Control, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA; Biomedical Research Unit, Asociación Benéfica PRISMA, Lima, Peru.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Gilman
authors.affiliation: Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University, Baltimore, USA.
authors.forename: Catherine H
authors.initials: CH
authors.lastname: Miele
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru; Program in Global Disease Epidemiology and Control, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA; Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University, Baltimore, USA.
authors.forename: William
authors.initials: W
authors.lastname: Checkley
authors.affiliation: Childhood Nutrition Research Centre, UCL Institute of Child Health, University College London, London, United Kingdom.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Wells
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Liam
authors.initials: L
authors.lastname: Smeeth
authors.affiliation: CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru; Department of Medicine, School of Medicine, Universidad Peruana Cayetano Heredia, Lima, Peru. Electronic address: Jaime.Miranda@upch.pe.
authors.forename: J Jaime
authors.initials: JJ
authors.lastname: Miranda
mesh_terms: D000328:Adult; D000368:Aged; D000531:Altitude; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010568:Peru / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012424:Rural Population; D014505:Urban Population
keywords: Altitude; Incidence; Obesity; Risk factors; Type 2 diabetes