Abstract
Aims/hypothesisThe aim of this study was to identify the contribution of small- and large-fibre neuropathy to erectile dysfunction in men with type 1 diabetes mellitus.MethodsA total of 70 participants (29 without and 41 with erectile dysfunction) with type 1 diabetes and 34 age-matched control participants underwent a comprehensive assessment of large- and small-fibre neuropathy.ResultsThe prevalence of erectile dysfunction in participants with type 1 diabetes was 58.6%. After adjusting for age, participants with type 1 diabetes and erectile dysfunction had a significantly higher score on the Neuropathy Symptom Profile (mean ± SEM 5.3 ± 0.9 vs 1.8 ± 1.2, p = 0.03), a higher vibration perception threshold (18.3 ± 1.9 vs 10.7 ± 2.4 V, p = 0.02), and a lower sural nerve amplitude (5.0 ± 1.1 vs 11.7 ± 1.5 mV, p = 0.002), peroneal nerve amplitude (2.1 ± 0.4 vs 4.7 ± 0.5 mV, p < 0.001) and peroneal nerve conduction velocity (34.8 ± 1.5 vs 41.9 ± 2.0 m/s, p = 0.01) compared with those without erectile dysfunction. There was also evidence of a marked small-fibre neuropathy with an impaired cold threshold (19.7 ± 1.4°C vs 27.3 ± 1.8°C, p = 0.003), warm threshold (42.9 ± 0.8°C vs 39.0 ± 0.9°C, p = 0.005) and heart rate variability (21.5 ± 3.1 vs 30.0 ± 3.7 beats/min, p = 0.001) and reduced intraepidermal nerve fibre density (2.8 ± 0.7 vs 5.9 ± 0.7/mm, p = 0.008), corneal nerve fibre density (12.6 ± 1.5 vs 23.9 ± 2.0/mm2, p < 0.001), corneal nerve branch density (12.7 ± 2.5 vs 31.6 ± 3.3/mm2, p < 0.001) and corneal nerve fibre length (8.3 ± 0.7 vs 14.5 ± 1.0 mm/mm2, p < 0.001) in participants with type 1 diabetes and erectile dysfunction. Erectile dysfunction correlated significantly with measures of both large- and small-fibre neuropathy.Conclusions/interpretationSmall-fibre neuropathy is prominent in patients with type 1 diabetes, and is associated with erectile dysfunction and can be objectively quantified using corneal confocal microscopy. This may allow the identification of patients who are less likely to respond to conventional therapies such as phosphodiesterase type 5 inhibitors.
Highlights
Erectile dysfunction in patients with type 1 diabetes mellitus poses a major clinical problem and was associated with poorer diabetes-related quality of life in the DCCT/Epidemiology of Diabetes Interventions and Complications (EDIC) cohort, in those with other complications including neuropathy [1]
Conclusions/interpretation Small-fibre neuropathy is prominent in patients with type 1 diabetes, and is associated with erectile dysfunction and can be objectively quantified using corneal confocal microscopy
We have shown a high prevalence of erectile dysfunction in men with type 1 diabetes mellitus, and demonstrated large- and small-fibre and autonomic neuropathy in men with erectile dysfunction
Summary
Erectile dysfunction in patients with type 1 diabetes mellitus poses a major clinical problem and was associated with poorer diabetes-related quality of life in the DCCT/Epidemiology of Diabetes Interventions and Complications (EDIC) cohort, in those with other complications including neuropathy [1]. It is principally mediated by impaired cavernosal vasodilatation due to a non-adrenergic, non-cholinergic nerve signalling defect, penile endothelial dysfunction and veno-occlusive disease; the relative contributions of each may differ between type 1 and type 2 diabetes [2]. Corneal confocal microscopy (CCM) is a rapid, non-invasive ophthalmic examination technique that objectively evaluates small-fibre neuropathy in patients with diabetes [13, 14] and is comparable with skin biopsy in the diagnosis of diabetic neuropathy [15, 16]
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