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Study analysis · Drug discoveries & therapeutics · 2026

Switching from daily growth hormone shots to a once-weekly version was linked to a 30% relative drop in triglycerides — but the 12-person study can't prove it was the shot.

In 12 adults with growth hormone deficiency, switching from daily to weekly growth hormone shots was followed by small improvements in weight, blood sugar, triglycerides, liver enzymes, and blood pressure over 2 years, but without a control group we can't know if the switch caused them.

Reading level
Low certainty
Level 2b · Individual cohort studyAssociation, not causationNo causal claims

Overview

What the study found

The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.

In simple terms

This study followed 12 people who switched from daily to weekly growth hormone shots. It shows that some health measures improved over time, but because there was no comparison group, we can't be sure the switch caused the improvements. It's like noticing your garden looks better after you change fertilizer, but you don't know if it was the fertilizer or just the weather.

What’s the bottom line?

Doctors switched 12 adults with growth hormone deficiency from daily shots to a weekly shot called somapacitan. They checked blood tests and body measurements over 2 years. Many things improved, but there was no comparison group.

How strong is this study?

The study is very small and didn't have a group that kept taking daily shots to compare against. That makes it hard to trust that the improvements were really due to the new shot. Also, the people knew they were getting a new treatment, which can affect results.

Reporting

40 / 100

  • COI disclosure+40/40
  • Data availabilitydata not shared
  • Code availabilitycode not shared
Methodology

14 / 100

  • Randomizationnot randomized
  • Blindingblinding unclear
  • Control groupno control group
  • Sample size (n=12)+1.2/20
  • Follow-up+10/10
Publication

100 / 100

Statistical

77 / 100

  • P-values+15/15
  • Effect size+20/20
  • Confidence intervals+15/15
  • Pre-registrationnot pre-registered

Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.

Where it sits

RCT reviews

Max 100

Randomized Trials

Max 90

Reviews of Cohort Studies

Max 85

Cohort Studies

Max 72

Reviews of Case-Control Studies

Max 63

Case-Control Studies

Max 58

Cross-Sectional & Case Series

Max 50

Expert Opinion

Max 5
StrongerWeaker
Cohort Studies
Level 2b
52

52 / 100

Probability of being correct

Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.

This design cannot establish causation — the findings describe an association, not a cause. This is a single-arm pre-post study without a control group, randomization, or blinding. The observed improvements could be due to natural variation, regression to the mean, placebo effects, or other unmeasured confounders. Therefore, causal inferences about the effect of switching from daily to weekly somapacitan cannot be made.

COI Unknown

Could not determine conflict of interest status

Not Disclosed

No conflict of interest or funding statement was provided in the manuscript, so potential conflicts and funder involvement cannot be assessed.

Undisclosed — Suspicious

The manuscript tests somapacitan, a proprietary weekly growth hormone formulation, but no industry affiliations, funding sources, or conflict of interest disclosures are present in the provided text. The absence of these statements limits transparency. The text also appears truncated at the end.

Key takeaways

  1. 01

    After 2 years: BMI dropped by 0.7 kg/m² (from 26.4 to 25.7; about 2.7% relative decrease).

  2. 02

    Fasting blood sugar dropped by 5.3 mg/dL (from 102.8 to 97.5).

  3. 03

    Triglycerides dropped by 40.9 mg/dL (from 136.5 to 95.6; about 30% relative decrease).

  4. 04

    Liver enzymes AST and ALT improved.

  5. 05

    Insulin resistance (HOMA-IR) improved by 0.7.

  6. 06

    Blood pressure improved (systolic -9.2 mmHg, diastolic -6.9 mmHg).

  7. 07

    HbA1c stayed the same.

  8. 08

    Other hormone levels did not change.

  9. 09

    These are absolute average changes in a small group of 12 patients.

  10. 10

    For example, BMI decreased by 0.7 kg/m² and triglycerides by about 41 mg/dL.

  11. 11

    Because there was no control group, we cannot know if the weekly shots caused the improvements or if they would have happened anyway.

  12. 12

    The study did not report absolute risk (like cases per 1,000 people) because the outcomes are lab measurements and body measurements, not disease events.

Surprising findings

  • Fasting glucose improved significantly, but HbA1c did not change at all over 2 years.Most people expect that if fasting blood sugar goes down, the 3-month average blood sugar (HbA1c) should also improve. The dissociation suggests different mechanisms.
  • Improvement in the liver enzyme AST was significantly associated with improvement in insulin resistance (HOMA-IR), but improvement in BMI was not.It's counterintuitive that liver enzyme changes track with insulin resistance while weight changes don't. This hints that liver health may be a key driver.
  • Triglycerides dropped by about 30% relative — a large effect for a simple formulation switch.A 30% relative reduction is comparable to some dedicated lipid-lowering interventions, yet this was just an observational switch in 12 people.
  • No changes in any other anterior pituitary hormones or related hormones over 2 years.Switching hormone formulations could theoretically disrupt the delicate pituitary axis, but this study found no such signals.

Practical takeaways

If you have adult growth hormone deficiency and are considering switching from daily to weekly somapacitan, discuss it with your endocrinologist — especially if convenience or adherence is a struggle.

This study is very small (n=12) and uncontrolled, so it cannot prove that weekly somapacitan causes metabolic improvements. Any switch should be based on your clinical context and doctor's advice.

low confidence

If you do switch, ask your doctor to monitor metabolic markers like fasting glucose, triglycerides, liver enzymes, and blood pressure over time.

Improvements may occur naturally or due to other factors; without a control group, you can't attribute changes solely to the switch.

low confidence

Don't interpret this as a reason to start growth hormone therapy for weight loss or metabolic health if you don't have a diagnosed deficiency.

This study only included adults with confirmed AGHD; results do not apply to people without growth hormone deficiency.

medium confidence

Why this study matters

Weekly shot, big triglyceride drop?

In 12 adults with AGHD, triglycerides fell by an absolute 40.9 mg/dL (from 136.5 to 95.6 mg/dL) at 2 years, which is about a 30% relative decrease (P<0.001). This was an uncontrolled pre-post change, so causation is not established.

Triglycerides are a key heart-risk marker, and a 30% relative drop sounds dramatic — but the small, uncontrolled design means it could be noise or regression to the mean.

Blood sugar improves but HbA1c doesn't

Fasting plasma glucose dropped by an absolute 5.3 mg/dL (from 102.8 to 97.5 mg/dL, P=0.010) at 2 years, but HbA1c stayed exactly the same at 6.2% (P=0.330). The study suggests this may reflect reduced hepatic insulin resistance rather than long-term glycemic control.

People often assume if fasting glucose improves, long-term blood sugar control must improve too. This dissociation is a great teaching moment about how different lab tests measure different things.

Liver enzymes and insulin resistance linked

AST improved by an absolute 2.8 U/L (23.1 to 20.3 U/L, P=0.006) and ALT by an absolute 3.6 U/L (19.3 to 15.7 U/L, P=0.024) at 2 years. In regression analysis, AST improvement was significantly associated with HOMA-IR improvement (β=1.195, 95% CI 0.178-2.212, P=0.026), but BMI improvement was not.

This hints that liver fat or liver insulin resistance may be a key link between growth hormone replacement and metabolic health — and that weight loss isn't the whole story.

Blood pressure drops after 2 years

Systolic blood pressure fell by an absolute 9.2 mmHg (139.4 to 130.2 mmHg, P=0.023) and diastolic by an absolute 6.9 mmHg (80.5 to 73.6 mmHg, P=0.022) at 2 years, though 1-year changes were not statistically significant for DBP (P=0.053).

A 9 mmHg drop in systolic BP is clinically meaningful if real, but without a control group it's impossible to know if the switch caused it.

Other hormones stay stable

Anterior pituitary hormones — ACTH, cortisol, TSH, free T4, LH, FSH, prolactin, and testosterone/estradiol — did not change significantly over 2 years. IGF-1 also remained stable within -1 to +1 SDS (103.5 to 101.2 ng/mL, P=0.352).

Safety is a major concern when switching hormone regimens. This suggests weekly somapacitan didn't disrupt other endocrine functions in these 12 patients.

But it's a 12-person uncontrolled study

The study had only 12 patients, no control group, no randomization, and no blinding. It was an exploratory real-world cohort. The authors themselves write that the design cannot establish causation.

This is a perfect case study in why we need to read past headlines. Many media outlets might report 'weekly hormone shots improve metabolic health' without mentioning the huge limitations.

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Standing

The people behind it

The researchers who wrote the study this analysis is built on.

Authored by

15 researchers

If this is your work, this is how we attribute it on Fit Body Science. Ichiro Abe is listed as the lead author.