The impact of blood pressure on cardiovascular disease (CVD) and mortality outcomes in older people with diabetes mellitus (DM) is not well quantified. Using a systematic review and meta-analysis of observational cohort studies, we aimed to compare the associations of blood pressure levels with cardiovascular and mortality outcomes in older people aged ≥ 65 years with or without DM.
Studies were identified from MEDLINE, Embase, Web of Science, and search of bibliographies to July 2022. Study-specific risk ratios (RRs) with 95% confidence intervals (CIs) were pooled.
Forty-five unique observational cohort studies (n = 2305,189 participants) assessing the associations of systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) levels with adverse cardiovascular outcomes were included. In the general population, the pooled RRs (95% CIs) of SBP ≥ 140 vs < 140 mmHg and per 10 mmHg increase for composite CVD/MACE were 1.26 (0.96-1.64) and 1.15 (1.08-1.23), respectively. The respective estimates were 1.56 (1.04-2.34) and 1.10 (1.04-1.18) for patients with DM. SBP ≥ 130 vs < 130 mmHg was not associated with an increased risk of adverse cardiovascular outcomes in both populations. SBP < 120 vs ≥ 120 mmHg was associated with an increased risk of all cause-mortality in the general population (n = 10 studies). DBP ≥ 90 mmHg was associated with an increased risk of some adverse cardiovascular outcomes in both populations. Interaction analyses suggested similar risk of outcomes in both populations.
Observational evidence suggests SBP and DBP confer similar cardiovascular and mortality risk in older adults in the general population and those with DM. A blood pressure target range of > 130/80 to < 140/90 mmHg may be optimal for patients ≥ 65 years with DM, but specific targets may need to be individualised based on patients' unique circumstances. Furthermore, findings do not support stringent blood pressure control in this population group. Definitive RCTs are needed to support these observational findings.

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