Ten-year incidence of diabetes in older Australians: the Blue Mountains eye study

Objective: To estimate the incidence of diabetes and impaired fasting glucose (IFG), and increased risk associated with the metabolic syndrome, in a representative population-based sample of older Australians. Design, setting and participants: The Blue Mountains Eye Study examined 3654 residents aged 49+ years (82.4% response rate) during 1992-1994, and re-examined 2335 (75.1% of survivors) during 1997-1999 and 1952 (75.6% of survivors) during 2002-2004; 2123 participants with normal blood glucose levels at baseline were considered at risk of developing incident diabetes. Main outcome measures: Incident diabetes (or IFG) was defined in participants at risk who were newly diagnosed by a physician during the follow-up or found to have a fasting blood glucose level ≥ 7.0 mmol/L (or 5.6-6.9 mmol/L). Kaplan-Meier cumulative 10-year incidence was calculated. Results: The overall 10-year incidence of diabetes and IFG was 9.3% and 15.8%, respectively. Participants with metabolic syndrome at baseline had a higher risk of incident diabetes than those without metabolic syndrome (29.2% v 8.6%). Baseline factors associated with incident diabetes were elevated fasting glucose level (adjusted odds ratio [OR], 4.5; 95% CI, 3.4-6.1 per mmol/L), obesity (OR, 2.0; 95% CI, 1.3-2.8), diabetes family history (OR, 1.7; 95% CI, 1.2-2.5), current smoking (OR, 1.6; 95% CI, 1.0-2.7) and high density lipoprotein cholesterol level < 1.0 mmol/L (OR, 2.4; 95% CI, 1.5-3.8). Similar baseline factors were associated with incident IFG. Conclusion: This population-based study provides data on the incidence of diabetes and IFG in an older, predominantly white population, and confirms that metabolic and lifestyle factors are major risk factors for diabetes.