Diabetes mellitus: prevalence and effect of morbidities in the oldest old. The Octabaix study.

Objectives: To describe the prevalence of diabetes mellitus (DM) in community-dwelling 85-year-olds and to study the factors associated.

Design: Cross-sectional.

Setting: Community-based survey study of seven primary healthcare centers.

Participants: Three hundred twenty-eight people born in 1924 and registered with primary healthcare centers.

Measurements: Information on sociodemographic variables, Barthel Index (BI), Spanish version of the Mini-Mental State Examination (MEC), Mini Nutritional Assessment (MNA), Braden scale for risk of pressure ulcers, Charlson Comorbidity Index, chronic diseases, social risk, quality of life, chronic drug prescriptions, and blood tests was recorded. Participants were defined as having DM according to self-report, physician diagnosis, antidiabetic prescriptions, or plasma glucose concentration 7 mmol/L or more. A comparative analysis was performed between participants with and without DM.

Results: The prevalence of DM in 328 octogenarians studied was 25.9%. Logistic regression showed an association between DM and BI (odds ratio (OR) = 1.03, 95% confidence interval (CI) = 1.00-1.05, P = .007), Braden risk score (OR = 0.87, 95% CI = 0.79-0.97, P = .01), thyroid disease (OR = 0.23, 95% CI = 0.06-0.92, P = .04), chronic drug prescriptions (OR = 1.28, 95% CI = 1.15-1.42, P < .001), white-cell count (OR = 1.34, 95% CI = 1.15-1.56, P < .001), low-density lipoprotein cholesterol (LDL-C; OR = 0.63, 95% CI = 0.43-0.92, P = .02) and folic acid level (OR = 1.04, 95% CI = 1.01-1.07, P = .005).

Conclusion: There is a high prevalence of DM at 85 years old. The presence of DM was positively associated with disability, drug prescription, white blood cell count, and folic acid level, whereas there was an inverse relationship between DM and Braden scale score, thyroid disease, and LDL-C. The effect of morbidities on DM may require a multidisciplinary approach to manage its complexity.