Objective: Anaemia is frequently found in patients with diabetes, in whom it is associated with increased morbidity and mortality. Low testosterone levels are also common in men with type 2 diabetes. We hypothesized that low testosterone levels are also associated with anaemia in men with type 2 diabetes, over the effects of chronic kidney disease.
Design: Cross-sectional cohort study, performed in 2005 in a tertiary diabetes clinic. Patients 464 men with type 2 diabetes.
Main outcome measure: Anaemia (haemoglobin (Hb) < 13.7 g/dl in men aged < 60, or < 13.2 g/dl in men aged 60 and older).
Results: About 24% of study participants had anaemia, which was associated with the presence and severity of chronic kidney disease, systemic inflammation, increased age, and reduced iron availability. In addition, testosterone levels were independently associated with reduced Hb levels, determining between 6 and 8% of the total variability in raw Hb levels in this population after adjusting for these other factors. Individuals with total testosterone level < 10 nmol/l (43% of the cohort) were more likely to have anaemia (adjusted odds ratio 1.7; 95% CI 1.1-2.8). Similarly, anaemia was twice as common in individuals with a calculated free testosterone of < 0.23 nmol/l (adjusted odds ratio 2.0, 95% CI 1.2-3.1).
Conclusions: These findings suggest that testosterone deficiency may contribute to the increased frequency of anaemia in men with type 2 diabetes. However, the appropriate clinical response to testosterone deficiency in anaemic patients remains to be established by prospective clinical trials.