Sermorelin and IGF-1 in Men's-Health Research

In plain English

IGF-1 (insulin-like growth factor 1) is the hormone the liver makes when growth hormone tells it to — it carries out many of GH's effects and is the number people watch when they study sermorelin IGF-1 responses. Sermorelin does not contain IGF-1. It nudges your pituitary to release growth hormone, and the IGF-1 rises downstream. In healthy older men, the more they were given (within the studied range), the more their GH and IGF-1 went up ^[2]. A related secretagogue raised IGF-1 in low-testosterone men too ^[7]. Here is what those studies measured, and what they did not.

Sermorelin IGF-1: dose-related responses in older men

The clearest sermorelin IGF-1 evidence comes from the aging-research literature. In healthy older men (mean age 68, n=10 old versus n=9 young), subcutaneous GHRH(1-29) at 0.5 mg and 1 mg twice daily for fourteen days produced dose-related increases in 24-hour GH and IGF-1 ^[2]. The response scaled with the dose: at the high dose, the men's GH and IGF-1 parameters no longer differed statistically from those of the young comparison group, and fasting glucose was unchanged ^[2].

The finding matters for how the axis is read. Endogenous GHRH-driven GH secretion declines with age, and the IGF-1 that GH drives declines with it. The study showed that supplying the GHRH signal can move the older men's 24-hour profile back toward the younger pattern — a reversal of an age-related decrease, measured over two weeks, not a longevity outcome.

Will sermorelin raise IGF-1 levels?

In healthy older men, GHRH(1-29) at 0.5-1 mg twice daily for 14 days produced dose-related increases in 24-hour GH and IGF-1; at the high dose, the GH and IGF-1 parameters no longer differed from those of young men ^[2]. The rise is downstream of GH release, not a direct IGF-1 supply, and it was measured in a small study over two weeks.

Sermorelin testosterone questions: what the GH-axis studies show

Sermorelin acts on the GH/IGF-1 axis, not the gonadal axis — but the two interact, which is why sermorelin testosterone questions are common. In healthy men aged 60-77, testosterone supplementation itself increased fasting GH and IGF-1 and raised both basal and pulsatile GH secretion, without altering the maximal somatotrope response to GHRH or to a GHRP ^[10]. In a separate clamp study, abdominal visceral fat was the dominant negative determinant of GHRH-stimulated GH release — accounting for 41% of the variance — while IGF-1 positively predicted secretagogue efficacy ^[9].

Testosterone also relaxes the brake on the axis: in middle-aged and older men infused with recombinant IGF-1, a high dose of testosterone attenuated IGF-1's feedback inhibition of both baseline and GHRH-stimulated GH secretion ^[11]. So the gonadal and somatotropic axes are wired together, but sermorelin is not studied as a testosterone-raising agent — it is studied as a GHRH-axis stimulus whose output testosterone happens to modulate.

Does sermorelin affect testosterone?

Sermorelin acts on the GH/IGF-1 axis, not the gonadal axis. In healthy older men, testosterone itself raised GH and IGF-1 and modulated the somatotrope response to GHRH ^[10], so the two axes interact — but sermorelin is not studied as a testosterone-raising agent. It is a GHRH-axis stimulus, and any testosterone link runs the other direction in the studies.

Sermorelin alongside testosterone in the research record

This is a research digest, not medical guidance, and no human protocol is recommended here. The literature shows testosterone and the GH/IGF-1 axis interact: testosterone raised GH and IGF-1 and blunted IGF-1 feedback in older men ^[11]. But combined-use safety in self-administered settings is not established, and the studies that exist measured hormones, not the long-term outcomes of stacking.

Secretagogues and IGF-1 in hypogonadal and men's-health research

The men's-health interest in GH secretagogues is grounded in a specific result: in hypogonadal men, growth hormone secretagogue treatment raised serum IGF-1 levels ^[7]. A companion review frames secretagogues within the modern management of body composition in hypogonadal males — explicitly beyond androgen-receptor-based therapy ^[8].

The framing is the important part. These are body-composition research questions about the GH/IGF-1 axis in men, where IGF-1 is the measured intermediate. They are not evidence that sermorelin builds muscle or strips fat in a given person; the controlled outcome data specific to sermorelin remain limited, and a 2025 Nature Reviews Endocrinology review situates GHRH analogs within a still-developing therapeutic picture ^[12].