It has long been recognised that erectile dysfunction (ED) is more common in men with diabetes, and various mechanisms have been cited as responsible, including penile smooth muscle cell damage, impaired blood or nerve supply and endothelial dysfunction. Whilst these functional changes in the penis have been the focus of much attention, little information is available on penile size per se in men with diabetes. Yet a common perception that is reinforced from a young age is that a large penis size is the only guarantee of better sexual and reproductive capabilities (Salama, 2015). Some have claimed that penile girth may be more important for sexual satisfaction than length (Francken et al, 2002). Either way, the presence of small penile dimensions may adversely affect quality of life beyond that of erectile dysfunction (Son et al, 2003).
Given that the tunica albuginea, which is integrally linked to penile extensibility within the penile tissue, is subject to damage via a number of mechanisms in diabetes, it is perhaps tempting to speculate that penile dimensions may be reduced in men with ED. However, to date, little evidence has been published to confirm this.
The present study by Nader Salama (summarised alongside) was carefully conducted to evaluate erect and flaccid penile size in men with diabetes and ED and to compare with two control groups: men with ED and no diabetes and men with neither condition. Measurements were standardised and the author claims they were quick to undertake and robust. The findings support the hypothesis that penile dimensions (length and circumference) are indeed reduced in men with ED, and even more so in those with comorbid diabetes. Several potential mechanisms are postulated, including chronic hypoxia and fibrosis, advanced glycation end-products and lipid-induced damage.
Do such findings have any practical implications? Our patients may report having a smaller penis and, rather than dismissing this claim, these findings afford a more scientific discussion of the evidence (“you are not alone compared with other men with diabetes and ED”) and to explain why this may occur. The author also speculates that this may be helpful in determining treatment options and monitoring treatment success in the future. Whether treatment of ED is associated with improvement in penile dimensions over time is largely unknown. For now, this is a helpful observation, although measuring penile dimensions routinely in clinical practice may be far off until a clear rationale for doing so becomes evident.
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Attempts to achieve remission, or at least a substantial improvement in glycaemic control, should be the initial focus at type 2 diabetes diagnosis.
9 May 2024