Two mechanisms, usually operating together.
Vascular. Sustained high blood glucose damages the endothelium — the lining of blood vessels — and impairs the relaxation of vessel walls that an erection depends on.
Neurological. Diabetic neuropathy affects the nerves carrying arousal signals. A tablet that improves blood flow cannot compensate for a signal that is not arriving.
That combination is why ED in diabetes tends to be more resistant to treatment than ED from a purely vascular cause.
The Scale of It
Erectile dysfunction is markedly more common in men with diabetes than in men without, and tends to appear roughly a decade earlier. It is also frequently the symptom that leads to a diabetes diagnosis in the first place — which is one of the strongest arguments for having ED assessed rather than treated silently online.
Undiagnosed Diabetes
If you have developed ED and have not had your blood glucose checked recently, that check should happen. An HbA1c is a routine blood test, and it is the single most valuable investigation in a man presenting with new erectile dysfunction.
Other signs worth mentioning to a GP alongside ED: increased thirst, passing urine more often, unexplained weight loss, fatigue, recurrent thrush or slow-healing wounds.
Does Medication Still Work?
Often yes, but response rates in diabetes are lower than in the general population, and higher doses are more frequently needed.
Practical implications:
- Do not conclude a medicine has failed after one attempt at a starting dose
- A dose increase, prescribed properly, is a common and reasonable next step
- Switching molecules is worth trying — response varies individually
- If oral treatment genuinely fails, other options exist and a urology referral is appropriate rather than a last resort
Glycaemic Control Matters
Improving blood glucose control does not reverse established nerve damage, but it slows further damage and improves vascular function. It is not a fast fix for ED and it is not a substitute for treatment — but it changes the trajectory, which a tablet does not.
The same applies to the rest of the cardiovascular package: blood pressure, cholesterol, smoking, weight and activity.
The GLP-1 Overlap
Many men with type 2 diabetes and obesity now take GLP-1 medicines, and weight loss generally improves erectile function through better vascular health and hormonal profile. That is a real benefit and worth knowing about.
It is also a reason to make sure whoever prescribes your ED medication knows everything you take. Care split across an NHS diabetes team and a private online ED service only works if both know what the other is doing.
Testosterone
Low testosterone is more common in men with type 2 diabetes and obesity, and it can blunt the response to PDE5 inhibitors. If ED is not responding as expected, a testosterone check is a reasonable part of the workup — it is a blood test, and it changes what the right treatment is.
The Point Worth Repeating
ED in a man with diabetes is a symptom of a systemic condition being managed, not a standalone inconvenience. Treating it through a service that never asks about your diabetes control, your other medicines or your cardiovascular risk is treating the least important part of the problem.