Testosterone Fell. Function Held. Six Years Inside Healthy Aging Men.

Most of what we know about aging men comes from men who were already ill. Infertility clinics, cardiology wards, diabetes registries. A study published in Andrology did something rarer and harder: it followed healthy men, selected precisely because nothing was wrong with them, and measured what six years of nothing but aging actually does.

Not sure if this applies to you? One-minute check.

The cohort nobody else has

The FAMe cohort, Fertility in Aging Healthy Men, was recruited in Munster between 2014 and 2016. The entry bar was severe: no smoking within the past year, no drug use, no regular medication beyond well-controlled blood pressure, thyroid or cholesterol treatment, no cancer history, no chronic infections, no previous fertility treatment. 197 men aged 18 to 84 made it through and were examined in full: hormones, semen analysis, validated questionnaires on erectile function and aging symptoms.

Then the researchers did the thing that separates a snapshot from a story. In 2020 they invited everyone back, and 117 men returned for the identical examination roughly six years later. Same measurements, same laboratory, same men. Almost every claim you have read about male aging comes from comparing different men of different ages. This is the rarer design: the same man, measured against himself.

What six years did to their hormones

Total and free testosterone fell significantly in most age groups over the six years. That part of the story is real, and it confirms what larger cross-sectional studies suggest. But the size and the destination matter more than the direction: mean total testosterone remained comfortably within the normal range in every single age group, at both time points. In the oldest group, men over 65 at the first visit, the mean was still around 20 nmol/L at follow-up, against a reference cutoff of 12.

FSH rose significantly in men over 35, while LH and SHBG stayed flat. Readers of this journal have seen that pattern before: FSH is the pituitary's signal to the sperm-producing machinery, and a rising FSH against stable output is the sound of a system compensating, working harder to hold the same result. It is the hormonal echo of what the same Munster group found inside testicular tissue itself, in the companion study we covered separately.

What six years did to their semen

The semen findings resist the usual doom narrative, and they do it with numbers. Sperm concentration stayed stable over time in every age group. Ejaculate volume declined in most groups, and total sperm count fell significantly in the 36 to 45 and 46 to 55 groups, but mean concentration and count remained within physiological limits across the board.

The one parameter that did move consistently was progressive motility, the fraction of sperm swimming forward. It declined in every age group, and fell below the reference range at follow-up only in the two oldest groups, men who were 56 or older at the first visit. Sperm vitality, oddly, improved over time in two groups, a reminder that biology rarely runs in one direction at once.

Put together: a healthy man's sperm production is not on the cliff edge the internet describes. It ages the way a well-maintained engine ages, gradually, measurably, and mostly within specification.

The twist: what actually drove symptoms

Here is where the study earns its place on this journal. Erectile function, measured with the standard IIEF questionnaire, declined moderately but progressively across the cohort. Aging-male symptom scores crept up too, from a mean of 22.3 to 25.3, which still sits in the "no symptoms" band of the scale. So far, exactly what you would expect.

Then the researchers asked the better question: what predicts which men decline? They restricted the analysis to men 45 and older and ran the candidates against each other.

Age did not predict the deterioration in erectile function (p = 0.13). Testosterone did not either (p = 0.52). HbA1c did (p = 0.002). The identical pattern appeared for aging-male symptoms: not age (p = 0.57), not testosterone (p = 0.18), but HbA1c, at p = 0.001.

HbA1c is glycated hemoglobin, the standard measure of average blood sugar over the preceding three months. And these HbA1c values were within the normal range: the authors are explicit that even in metabolically healthy men, subtle variations in glycemic control tracked with erectile function. Within a cohort of healthy men, the variation in long-term blood sugar control was a stronger predictor of sexual decline than either of the two things men actually worry about.

Symptoms of low testosterone, without low testosterone

The authors put the conclusion carefully, and it deserves quoting in spirit: older men may exhibit hypogonadism-like symptoms in the absence of bona fide hypogonadism. The tiredness, the low drive, the fading function that send men to search engines at two in the morning were present in some of these men, while their testosterone sat within range.

That cuts in two directions, and both matter clinically. First: a man with those symptoms deserves an actual measurement, properly done, before anyone reaches for a diagnosis, because the symptom list alone cannot distinguish a hormone problem from a metabolic one. Second: when the measurement comes back normal, the work is not over. It has just moved. In this cohort the trail led to glycemic control, which is measurable, and unlike age, changeable.

The limitations, stated plainly

Eighty-three of the 197 men did not come back, and men who return for a voluntary six-year follow-up may differ from men who do not. The groups are small once divided by age, twelve to twenty-seven men each. Testosterone was measured by immunoassay, albeit one calibrated quarterly against mass spectrometry. And the selection cuts both ways: this study cannot tell you what happens to the average man, because the average man would not have qualified for it.

But that last limitation is also the finding. These men were selected for health, and health is what they kept. The study does not show that aging is harmless. It shows what aging looks like when nothing else is allowed to pile on top of it.

Why this matters for a man in his fifties

Two numbers from this study belong in every consultation with a man worried about his hormones. The first is his testosterone, measured properly, because genuine deficiency exists and is treatable. The second is his HbA1c, because in the healthiest cohort ever followed this way, that number predicted the decline in function and wellbeing better than age or testosterone did.

Neither number is visible from the outside. A man can carry rising blood sugar for a decade inside a normal-looking body, and the first symptom he notices may arrive in the bedroom rather than on a laboratory form. That is why the assessment we run looks at hormones, metabolic markers and body composition together, as one system, because that is how they behave.

The message of this cohort is genuinely encouraging, and it is not soft: reproductive aging in healthy men is slow, mostly quiet, and largely preserved into the seventies. The variable that separates men within it is metabolic, and metabolic variables can be found early and moved.