Introduction: Both low testosterone levels and erectile dysfunction (ED) are highly prevalent in men with type 2 diabetes. Lower testosterone levels are known to be associated with worsening severity of ED as assessed using the International Index of Erectile Function score (IIEF). Testosterone deficiency and erectile dysfunction are both independently correlated with increased risk of cardiovascular disease.
Aim: To investigate the effect of low testosterone and erectile dysfunction on Health-Related Quality of Life (HRQoL) in a cohort of 356 men with type 2 diabetes.
Method: Total testosterone (TT), bioavailable testosterone (BT) and SHBG levels were analysed from morning blood samples. Free testosterone (cFT) levels were calculated using Vermeulens equation. SF-36 scores were obtained from 356 patients, of whom 126 completed IIEF questionnaires. Data were analysed using PASW software. Local Ethical Committee approval was obtained.
Results: Mean baseline characteristics were: age 58.5 (±8.1), TT 12.17 nmol/l (±5.86), BT 3.84 nmol/l (±1.64), cFT 260 pmol/l (±0.14). Mean SF-36 score was 67.7 (±17.3) and mean IIEF score was 12.16 (±4.29).
Regression analyses were carried out correcting for age, BMI, HbA1c, smoking, alcohol consumption and cardiovascular disease.
Total testosterone levels significantly correlated with HRQoL scores (r=0.353, P=0.044, n=356) when corrected for SHBG.
In the 126 patients who completed IIEF questionnaires, IIEF scores significantly correlated with total SF-36 scores (r=0.491, P=0.003). IIEF scores also correlated with SF-36 domains: Physical (r=0.500, P=0.003), Physical role limitations (r=0.350, P=0.031), Social (r=0.445, P=0.022), Vitality (r=0.383, P=0.025), Pain (r=0.428, P=0.012), and General health (r=0.408, P=0.001).
IIEF scores significantly correlated with levels of TT (r=0.546, P<0.001), BT (r=0.506, P=0.004) and cFT (r=0.532, P<0.001). TT was corrected for SHBG in addition to the above factors.
Conclusion: This is the first study to report that lower testosterone and severity of erectile dysfunction are both independently associated with reduced quality of life in diabetic men.