Background: The anaemia of diabetes is strongly associated with renal microvascular disease and is associated with increased morbidity and mortality.
Aim: To examine the prevalence, associations and consequences of anaemia complicating diabetes in an urban Australian population.
Patients and Methods: The Fremantle Diabetes Study Phase II (FDS2) includes 1551 participants with type 2 and 139 with type 1 diabetes recruited between 2008 and 2011. Anaemia was ascertained using World Health Organisation criteria at study entry (haemoglobin <130 g/L in males, <120 g/L in females). The cohort was followed to death/census at end-March 2014, a mean follow up of 4.3±1.1 years.
Results: At baseline, the 1728 participants with available full blood count data had a mean±SD age of 63.9±13.6 years, 52.1% were male, and their median [inter-quartile range] diabetes duration was 10.0 [3.0-16.7] years. The 201 (11.6%) who were anaemic were older at study entry (70.0±13.4 vs 63.1±13.4 years, P<0.001), but had a similar age at diagnosis and thus longer diabetes duration (16.0 [11.8-21.1] vs 8.0 [2.7-16.0] years, P<0.001) than those who were not anaemic. Independent associates of anaemia included Aboriginality, longer diabetes duration, higher urinary albumin:creatinine, and lower estimated glomerular filtration rate (eGFR). An eGFR of 15-29 ml/min/1.73m2 increased the risk 22-fold. During follow-up, 28.9% of the anaemic group vs 7.4% of the non-anaemic group died (P<0.001). Cox proportional hazards modelling with age as time-line showed that all-cause mortality was predicted by male sex, Aboriginality, current smoking and eGFR category, while being married/in a de facto relationship was protective. After adjustment using the most parsimonious model, anaemia independently predicted increased mortality (hazard ratio (95% CI): 1.72 (1.20-2.47), P=0.003).
Conclusions: Anaemia is an independent predictor of death in patients with diabetes. Haemoglobin measurement is a valuable prognostic indicator that should be considered as part of regular monitoring.