Small fibre pathology is associated with erectile dysfunction in men with type 2 diabetes

Aims: The aim of this study was to evaluate the contribution of small and large fibre neuropathy to erectile dysfunction (ED) in men with type 2 diabetes (T2D). Methods: Measures of small and large fibre neuropathy were evaluated in 49 participants with T2D and 20 age-matched controls. Results: ED was present in 59% of participants with T2D. There was no difference in age, duration of diabetes, blood pressure, lipid profile, vibration perception threshold (V) (14.3 ± 7.8 vs 11.2 ± 6.6, P =.429), peroneal (41.4 ± 8.2 vs 44.8 ± 4.4, P =.10) and sural (45.4 ± 5.6 vs 47.1 ± 5.8) nerve conduction velocities (m/s), cold (25.1 ± 3.8 vs 26.2 ± 2.9, P =.815) and warm (43.2 ± 4.0 vs 41.0 ± 3.8) perception thresholds (°C), and deep breathing heart rate variability (18 ± 8 vs 18 ± 8) between participants with and without ED. However, intraepidermal nerve fibre density (no./mm²) (4.6 ± 2.8 vs 13.7 ± 2.7, P <.001), corneal nerve fibre density (no./mm²) (23.5 ± 6.8 vs 31.3 ± 8.2, P <.001), corneal nerve fibre branch density (no./mm²) (55.4 ± 35.3 vs 97.7 ± 46.4, P =.004), corneal nerve fibre length (mm/mm²) (17.6 ± 6.8 vs 27.3 ± 6.8, P <.001), and sural (7.7 ± 6.1 vs 14.6 ± 6.7, P =.003) and peroneal (2.5 ± 2.0 vs 4.7 ± 2.0, P =.003) nerve amplitudes were significantly lower in participants with ED compared with those without ED. Conclusion: ED affects almost 2/3 of men with T2D and is associated with small nerve fibre damage but preserved nerve conduction and cardiac autonomic function. Corneal confocal microscopy may serve as a useful non-invasive imaging method to identify small fibre damage in patients with T2D and ED.