Diabetes and Male Fertility: What It Changes

Usually not by itself. Diabetes reaches fertility by three separate routes, and mixing them up is what makes this confusing. Two of them are mechanical: whether you can get and keep an erection, and whether the semen comes forwards when you ejaculate. The third is about the sperm itself — count, movement and DNA integrity.

On the evidence below, the mechanical two are the ones that most often stop a pregnancy happening, and both are findable with ordinary tests and often treatable. The effects on the sperm itself are real on average but modest, inconsistent between studies, and in at least two series were invisible on a routine semen report.

So the useful question is not "has diabetes damaged my fertility". It is "which of the three is happening to me", and that is answerable in about two appointments.

The erection, by a wide margin. Across 145 studies and 88,577 men, the pooled prevalence of erectile dysfunction in diabetes was 52.5% (95% CI 48.8 to 56.2) — prevalence 37.5% in type 1 and 66.3% in type 2 — and the pooled odds against healthy controls were about 3.6 times higher (OR 3.62, 95% CI 2.53 to 5.16) (Kouidrat 2017, Diabetic Medicine).

That is a different subject from sperm, and it has its own page: how erectile dysfunction affects conception, and what it can be an early warning of. Worth reading if this is your situation, because it also covers the Indian data and the question of what else to get checked.

Second is retrograde ejaculation, where the bladder neck does not close and semen goes backwards instead of forwards. Diabetes is one of the common causes, alongside spinal cord injury and prostate surgery (Konstantinidis 2025, Diagnostics). The tell is a dry or very small ejaculate, and the test is simple: a urine sample examined straight after ejaculation. Which ejaculation problems actually affect fertility sets out the numbers and what can be done, including when sperm can still be recovered and used.

Both of these are worth raising even if they feel like the harder thing to say in a clinic room. They are also the two most likely to be missed if you do not say them, because neither shows up on a blood test.

Less than the internet suggests, and the most interesting finding is that the damage can be invisible on the standard report.

A meta-analysis of 44 studies, with 1,386 men with diabetes in the diabetes arm, found lower pooled averages across the board against non-diabetic controls: semen volume lower by 0.45 mL (95% CI -0.63 to -0.27), total sperm count lower by 13.12 million (-18.43 to -7.82), concentration lower by 11.73 million per mL (-21.44 to -2.01), progressive motility lower by 14.37 percentage points (-21.79 to -6.96), and testosterone lower by 0.37 (-0.63 to -0.12) (Zhong 2021, Diabetology & Metabolic Syndrome). The authors attach their own warning to this: the number and quality of the included studies is limited and the conclusions need verifying by better research.

Two smaller studies point somewhere more specific. In 27 men with insulin-dependent diabetes compared against 29 non-diabetic men attending a fertility clinic, the conventional semen parameters did not differ significantly at all, apart from a small reduction in volume (2.6 vs 3.3 mL). What did differ was DNA: nuclear DNA fragmentation was 53% against 32% (p<0.0001), with more mitochondrial DNA deletions as well (Agbaje 2007, Human Reproduction). And in a retrospective series of men with type 2 diabetes having assisted reproduction, seminal parameters again showed no significant difference from controls, while HbA1c analysed as a continuous variable was associated with higher DNA fragmentation (Moura 2025, JBRA Assisted Reproduction).

Both of those are small — 27 men in one, a single-centre record review in the other — so the right conclusion is that a normal semen report does not settle the DNA question, not that your DNA is damaged. What a sperm DNA fragmentation test can and cannot tell you covers where that test is useful and where it is oversold.

Here is the honest answer, which is less satisfying than the usual one.

The evidence points at the degree of control rather than the diagnosis. In both series above, having type 2 diabetes did not by itself predict worse semen parameters, but HbA1c as a continuous measure tracked DNA fragmentation. That is consistent with control mattering.

What has not been done, in anything retrieved for this page, is the study that would settle it: take men with poor control, improve it, and measure semen parameters, DNA fragmentation or live birth afterwards. No such intervention result is cited here because none was found. So the claim that tightening control improves your fertility is plausible and unproven, and anyone stating it as established is going beyond the evidence.

None of which is an argument against controlling it. The reasons to control diabetes stand on their own and do not need a fertility justification. The point is only that you should not expect a measured fertility gain as the payoff, and you should not delay a fertility work-up while waiting for one.

Weight and general lifestyle sit next to this and have been looked at more directly: what weight does to male fertility and which lifestyle changes have actually been measured.

If you have diabetes and you are trying to conceive, this is a short list and it is not expensive.

1. An HbA1c, if you have not had one recently. It is the number the DNA fragmentation signal above tracked against, so it is worth having in front of you rather than a fasting sugar from last year.
2. A semen analysis, done to the WHO sixth-edition standard. Ask the laboratory which edition of the WHO manual they work to, because that is the answer that tells you whether the report can be compared with anything.
3. If your ejaculate is dry, very small, or has got smaller, say so and ask for a urine sample to be examined straight after ejaculation. That is the test that separates retrograde ejaculation from a production problem, and it will not be done unless somebody mentions the symptom.
4. If erections are the problem, raise it as its own item rather than folding it into the fertility conversation. It is treatable, and it is also worth checking for its own sake.
5. Expect a repeat semen analysis a few months later rather than a decision on one sample. Sperm in any given sample was produced over the preceding weeks, so about three months is the usual interval before a repeat means much.

One question worth asking your own doctor, phrased so it does not put anyone on the defensive: we are trying for a child — is there anything in my current treatment worth reviewing with that in mind, and would you rather I checked with you before changing anything? That keeps the decision where it belongs and still gets the subject on the table. The one thing to raise unprompted is that you want children, before any testosterone is prescribed, because testosterone suppresses sperm production.

On reading the report you get back: how to read a semen analysis line by line, and what the test does and does not reveal. A low number on one sample is a reason for a second sample, not a verdict.

It is a hard thing to sit with — managing a condition that already asks for daily attention, and being told it may be part of why this has not happened yet. Most of what is on this list is a test rather than a treatment, which means most of it comes back as information you did not have before.

Several things are commonly said about diabetes and male fertility, including on the previous version of this page, that the sources cited here do not support.

• That improving glycaemic control improves fertility outcomes. No intervention study was retrieved in which control was improved and semen parameters, DNA fragmentation or live birth were then measured. The association with HbA1c is cross-sectional. Plausible, not shown.
• That diabetes causes miscarriage or birth defects through sperm DNA damage. Nothing cited here measures miscarriage or congenital anomaly against paternal diabetes. The DNA fragmentation findings are laboratory measurements in small samples, and no clinical outcome was attached to them. This claim was on the previous version of the page and has been removed rather than softened.
• That erectile dysfunction in diabetes responds worse to treatment. Also on the previous version, also unsupported by anything retrieved. The prevalence finding is well evidenced; a claim about treatment response is a separate claim and was not measured in these sources.
• That diabetes blocks the tubes through infection. The previous version asserted that diabetes-related prostatitis and epididymitis cause scarring and blockage. No source was retrieved for it and it is gone.
• That the semen findings are reliable. The meta-analysis authors say so themselves: limited number and quality of included studies, conclusions needing verification. Two of the three sperm studies here found no significant difference in routine parameters at all. Treat the averages as a tendency in populations, not a prediction about one man.
• A WHO cut-off that tells you whether you are fertile. No WHO reference limit is quoted on this page, and that is deliberate. The manual's own contributors have written that the WHO reference limits are often misinterpreted as strict boundaries between fertility and infertility, and that a valid andrological diagnosis cannot rest on semen results alone (Bjorndahl 2023, Andrology).
• Which treatment you should have. Drug names and sperm-retrieval techniques were listed on the previous version of this page with no source attached to any of them. That is a conversation with a urologist or andrologist who has your results, not a list on a web page.

And the house position, which applies here as much as anywhere: sometimes the answer is testing, timing or a simpler treatment rather than IVF. A man with diabetes, a normal semen analysis and an erection problem needs the erection problem treated, not a cycle.