If you are going to spend money on this, spend some of it before you start.
That sounds like an odd priority when you have just ordered a vial and want to get going. But almost everything a blood test tells you here is a comparison, and a comparison needs two points. An IGF-1 of 180 is reassuring if you started at 120. It is unremarkable if you started at 190. Afterwards, there is no way to tell those apart.
There is a second reason. With the growth hormone compounds, the number that tells you it is working is the same number behind the main thing to watch. IGF-1 going up is the effect you are paying for. IGF-1 going up is also what nudges insulin sensitivity in the wrong direction. You cannot buy one without the other, which is a good argument for knowing the number instead of guessing at it.
Why you need a baseline before starting
Every use of a lab result here comes down to one question. Did it move, by how much, and which way.
Without a starting point you have a number and a reference range to hold it against, and a reference range describes a population rather than you. Plenty of people sit near the top or bottom of normal for their whole lives, and a result inside the range can represent a large personal change while a result outside it can be someone's ordinary.
Our guide on how long peptides take to work makes the same argument about how you feel. It applies harder to labs, because a lab result is measurable in a way a feeling is not.
Run the panel before you start. If you have already started, run it now, because a reading at week six is still better than no reading at all and it becomes the baseline for everything after.
Does it matter when you get tested?
A baseline only works if the second reading is taken the same way as the first.
Fasting glucose means nothing unless you actually fasted, and it means something different after ten hours than after fourteen. HbA1c is the forgiving one, since it averages three months and ignores what you ate this morning. IGF-1 is steadier than most hormones across a day, and it still sits downstream of your last dose.
None of the rules are interesting, which is probably why they get skipped. Use the same lab, because different labs run different assays and set their reference ranges accordingly, so a change between them can be the lab rather than you. Same time of day, same fasting state, and the same gap since your last dose, which for a nightly compound means going in at roughly the same number of hours after it every time.
Change any of those between visits and the second reading is measuring something the first one was not.
What bloodwork to run before starting peptides
This is what a clinician would typically look at for this class of compound. It is a list, not a protocol, and the interpretation belongs to whoever ordered the tests.
IGF-1
IGF-1 is how you find out whether anything is happening at all. Growth hormone itself is difficult to measure, because it comes out in pulses and a single draw catches whichever part of the pulse you happened to hit. IGF-1 is what growth hormone produces downstream, it stays fairly steady through the day, and it goes up if a secretagogue is doing its job. How far it goes up is the nearest thing to a dose response you can see.
HbA1c and fasting glucose
These are the safety half of the same story, and there is a whole section on them below. In short: the thing making your IGF-1 rise is also nudging your blood sugar, and these two tests are how you watch that.
A comprehensive metabolic panel
One test covering liver enzymes, kidney function and electrolytes, and usually cheap because it is bundled as standard.
The kidney numbers deserve more attention than they get. Most of these compounds leave the body through the kidneys, so how well yours are working affects how long anything hangs around. Reduced function is also more common than people assume and often nobody has mentioned it, because it causes no symptoms until it is well advanced. Our guide on peptides after 65 goes into that.
Thyroid function
Growth hormone changes how the body converts thyroid hormone, and TSH and free T4 are on most standard panels anyway, so this one is usually free.
Nothing dramatic is expected here. The reason to have it is more practical. Fatigue is a common thing to report, thyroid is the first thing tested when you report it, and a slightly odd result with no starting point to compare it against can send a perfectly reasonable doctor down a road you did not need to travel.
A lipid panel
Growth hormone changes how the body handles fat, and a lipid panel is cheap and usually included anyway. Take it while you are there.
A full blood count
Nothing here should move this one. It is included because it comes as standard, and because an odd result of any kind is much easier to make sense of when somebody can see where you started.
If you are on a GLP-1 drug the picture is simpler, because it was prescribed and whoever prescribed it decides what to monitor. Kidney function, HbA1c and sometimes liver markers are the usual set. Our comparison of the three covers what the trials measured.
Do peptides raise blood sugar?
Growth hormone makes your body less responsive to insulin. That is not a side effect somebody stumbled on later, it is part of what growth hormone does, and it has been understood for decades. Insulin is what moves sugar out of your blood and into cells, so when it works less well, blood sugar sits higher for longer.
In the two-year trial of MK-677 in older adults, fasting glucose rose by an average of 0.3 mmol/L, around 5 mg/dL, and insulin sensitivity decreased.[^1] In the trial record for a sarcopenia study, HbA1c rose slightly in most subjects on the compound, and one participant had a rise in both HbA1c and fasting glucose that returned to normal after the dose was reduced and diet changed.[^2]
Here is the part I did not expect when I went looking.
In an earlier study, fasting glucose and fasting insulin came back unchanged, while a glucose tolerance test showed impaired handling at both two and eight weeks.[^3]
Fasting glucose is the number almost everyone would check, and it can read perfectly normal while the thing you were checking for has already started. HbA1c catches more of it because it averages three months instead of one morning. A glucose tolerance test catches more still, and nobody is ordering one of those on their own initiative.
None of which is alarming on its own. It is an argument for knowing your HbA1c before you start, since that is the marker most likely to show what is actually happening.
If you already have diabetes or prediabetes
Existing diabetes, prediabetes or insulin resistance changes this calculation. Worsening glucose control in that group is documented, not hypothetical. That does not automatically rule anything out, and plenty of people manage two things at once. It does mean the conversation belongs with whoever looks after your glucose, and it belongs before you start rather than after a surprising result.
At the far end of the same physiology, glucose metabolism disorders are among the most common complications of acromegaly, where growth hormone runs high for years.[^4] Our guide on the cancer question covers what else that end of the range shows.
What your results cannot tell you
Whether your IGF-1 is too high
Reference ranges describe how the number varies naturally with age and sex. They were never built for somebody deliberately pushing it up.
So nobody can tell you what a raised level means in your case, or where the line is, because the population doing this has never been followed. Our guide on the cancer question sets out why that gap matters and what the surrounding evidence does show.
Whether the compound is working
IGF-1 rising confirms the compound got where it was going. It does not tell you that anything you actually care about changed, and the trial record is unhelpful on exactly that point: in the studies that measured both, markers moved and function did not.
Whether a change came from what you took
Labs move for all sorts of reasons. One reading before and one after is a comparison rather than an experiment, and anything else that changed in those weeks, a new job, less sleep, a different diet, is a competing explanation you cannot rule out.
How much does peptide bloodwork cost?
These panels are not free, and direct-to-consumer pricing varies enough that quoting a figure here would be misleading within months.
The comparison worth making is against the compound itself. A full baseline panel can easily cost more than a month of what you are considering, which is a genuinely annoying position to be in: one more vial, or knowing where you started. Our guide on cost per dose covers the arithmetic on the other side of that.
Two routes make it cheaper. Much of this appears on a standard annual panel, so timing your baseline to a check-up you were having anyway costs almost nothing extra. And the follow-up panel can be narrower than the baseline, because the point of the second test is the markers that were expected to move, not all of them.
If the money only stretches to one test, make it the baseline. A starting point with no follow-up remains useful later. A follow-up with no starting point is close to worthless.
Who can order these tests
Any doctor can order all of this, and if you would rather not have the conversation, direct-to-consumer panels exist and cover most of it.
The case for going through a clinician has nothing to do with gatekeeping. It is that a result only means something held against your history, and a service that returns a number and a coloured bar has not done that part.
Tell whoever orders it what you are taking, before the results come back. Our guide on drug testing covers why IGF-1 is the line to flag. An unexplained raised result there prompts a real investigation, and the explanation is a sentence you could have offered at the start.
What to do if a result comes back high
Interpretation belongs to whoever ordered the test. The sequence before that does not, and people get it wrong in a predictable way.
Repeat an unexpected result before you do anything about it. Single readings drift, labs disagree with each other, and a fasting glucose taken after a bad night's sleep is not a trend. The common mistake is stopping something or changing something on one number, and a repeat test costs you a week and settles it.
Watch direction more than position. A value inside the reference range that has moved a long way is more informative than a value slightly outside it that has not moved at all, which is the whole argument for having a baseline.
Take it to somebody, with the context. A result, plus what you are taking, plus when you took it last, gives a clinician something to work with. A bare number leaves them guessing.
Where this stops being useful
Which tests you specifically need, which depends on your history, your medications and what you are taking.
What your results mean, which is what the person who ordered them is for.
Any target number. This page names no ranges and no goals deliberately, because there is no established target for a pharmacologically elevated IGF-1 and inventing one would be worse than saying so.
Common questions
What bloodwork should I get before starting peptides?
For growth hormone compounds, typically IGF-1, HbA1c and fasting glucose, a comprehensive metabolic panel covering liver and kidney function, a lipid panel and a full blood count. The exact set is a question for whoever orders it.
Does IGF-1 tell me if it is working?
It tells you the compound reached its target and raised growth hormone. It does not tell you that anything you actually wanted has changed, which is a separate question our guide on how long peptides take to work covers.
How often should I retest?
There is no established interval for any of these compounds. What matters more is having a baseline at all, since everything after is measured against it.
Will these raise my blood sugar?
Growth hormone reduces insulin sensitivity, and trials of MK-677 show fasting glucose rising and insulin sensitivity falling.[^1] The size of that effect in any individual has not been characterised.
My fasting glucose is normal. Am I fine?
Not necessarily. In one study fasting glucose and insulin were unchanged while a glucose tolerance test already showed impaired handling.[^3] HbA1c is the more informative routine test, because it averages three months.
Does it matter what time I get tested?
Considerably. Use the same lab, the same time of day, the same fasting state and the same interval since your last dose. Change any of those and the second reading measures something different from the first.
How much does this cost?
Enough to be a real decision. A full baseline panel can cost more than a month of what you are taking. Timing it to an annual check-up you were having anyway is the cheapest route, and the follow-up can be narrower than the baseline.
What do I do if a number comes back high?
Repeat it before acting on it. Single readings drift and labs vary, and stopping something on one unexpected value is the common mistake. Then take the result to somebody, along with what you are taking and when you last took it.
Can I use a direct-to-consumer panel?
You can, and most include the relevant tests. What they do not include is somebody reading the result against your history, which is the part that turns a number into information.
Should I tell my doctor what I am taking?
Yes. An unexplained raised IGF-1 prompts an investigation, and the explanation takes one sentence.
I already started without a baseline. Is it too late?
No. Test now and treat that as your baseline. It is worse than a true starting point, and considerably better than nothing.
Sources
[^1]: Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults. Two-year randomised controlled trial. Reported as increasing fat-free mass by approximately 1.1 kg without improvement in strength or function, with fasting blood glucose increasing by an average of 0.3 mmol/L, around 5 mg/dL, and insulin sensitivity decreasing.
[^2]: Trial record describing MK-677 in a sarcopenia population, as reproduced in US Patent 7,442,706. Patent document reproducing trial data. Records slight elevations in HbA1c in most subjects receiving MK-677, with those affected tending to have higher BMI and HbA1c and reduced insulin sensitivity at baseline. Describes one 81-year-old participant whose HbA1c and fasting glucose rose after crossover from placebo, with HbA1c returning to normal following a dose reduction to 10 mg daily and a change of diet.
[^3]: Svensson J, et al. Trial of MK-677 in obese males, 1998. Randomised trial. Fasting glucose and fasting insulin were unchanged, while an oral glucose tolerance test showed impaired glucose homeostasis at both two and eight weeks.
[^4]: Glucose metabolism disorders in acromegaly. Reported in the endocrinology literature, with prevalence figures for diabetes and prediabetes in acromegaly commonly given in the range of 12 to 56% across studies.