To evaluate whether low glycosylated hemoglobin (HbA1c), blood pressure (BP), and total cholesterol (TC) are associated with lower risk of all-cause mortality in very old individuals with type 2 diabetes mellitus.DESIGN:
Population-based cohort study.SETTING:
Primary care database in the United Kingdom.PARTICIPANTS:
Individuals aged 80 and older with type 2 diabetes mellitus (N = 25,966).MEASUREMENTS:
Associations between baseline HbA1c, BP, and TC and all-cause mortality were evaluated in Cox proportional hazards models. Analyses were adjusted for sex, age, duration of diabetes mellitus, lifestyle variables, HbA1c, BP, TC, comorbidities, prescribing of antidiabetic and cardiovascular drugs, and participants' general practice.RESULTS:
There were 4,490 deaths during follow-up (median 2.0 years; mortality 104.7 per 1,000 person-years). Mortality in participants with low (<6.0% (<42 mmol/mol)) or high (≥8.5% (≥69 mmol/mol)) HbA1c was similar to that in those with the reference HbA1c (8.0–8.4% (64–68 mmol/mol)). Mortality was lowest in individuals with HbA1c of 7.0–7.4% (53–57 mmol/mol) (80.9 per 1,000 person-years, adjusted hazard ratio (aHR) = 0.80, 95% confidence interval (CI) = 0.70–0.91, P = .001). Mortality was higher in individuals with lower BP (e.g., <130/70 mmHg, 151.7 per 1,000 person-years, aHR = 1.52, 95% CI = 1.34–1.72, P < .001 vs reference BP <150/90 mmHg) and in the lowest TC category (<3.0 mmol/L, 138.7 per 1,000 person-years, aHR = 1.42, 95% CI = 1.24–1.64, P < .001 vs reference TC 4.5–4.9 mmol/L). The relationship between TC and mortality varied according to sex and prescription of lipid-lowering drugs.CONCLUSION:
Low HbA1c, BP, and TC may be associated with higher mortality in very old adults with type 2 diabetes mellitus. Further research is required to understand these associations and to identify optimal treatment targets in this population.