Does MK-677 raise blood sugar? Yes. Higher blood sugar and lower insulin sensitivity are the most consistent lab findings across MK-677 trials. Over 12 months on 25 mg/day, average fasting glucose rose a modest 5 mg/dL, but more than a third of participants on MK-677 moved from normal into the prediabetes range, and some had to lower the dose or stop. In the largest trial, blood glucose rose in 15.4% of patients on MK-677 vs 4.6% on placebo. In the 12-month trial, the changes reversed when people switched to placebo.
This page gathers every glucose, insulin and HbA1c result from the human trials, explains what the numbers mean, who seemed most affected, and what the investigators did about it. For the compound itself, see our MK-677 (ibutamoren) review.
Why MK-677 raises blood sugar
MK-677 raises growth hormone (GH) and IGF-1 (FDA 2024). Growth hormone works against insulin, and the authors of the 12-month trial put it simply: “Both GH and MK-677 increase insulin resistance and blood glucose in the elderly” (Nass 2008). Approved GH medicines carry warnings about glucose intolerance and diabetes, and the FDA says it is concerned the same risks apply to ibutamoren (FDA 2024).
Blood sugar results in MK-677 trials
| Study | People, dose, length | Glucose and insulin findings |
|---|---|---|
| Chapman 1996 | 32 adults aged 64–81; up to 25 mg/day; 4 weeks | Fasting glucose 5.4 → 6.8 mmol/L (about 97 → 122 mg/dL) on 25 mg; up 25% at 2 weeks and 27% at 4 weeks; rise linked to body mass index |
| Chapman 1997 | 9 GH-deficient men; 10 or 50 mg/day; 4 days | Fasting and after-meal insulin and after-meal glucose rose |
| Murphy 1998 | 8 dieting adults; 25 mg/day; 7 days | One participant had a fasting glucose of 142 mg/dL on day 14 |
| Svensson 1998 | 24 obese men; 25 mg/day; 8 weeks | Fasting glucose and insulin unchanged, but an oral glucose tolerance test got worse at 2 and 8 weeks; one man’s glucose hit 10 mmol/L at week 6 and fell back a week later |
| Murphy 1999 | 187 adults 65+; 5–50 mg/day; 2–9 weeks | High glucose was the most common lab side effect; in the 9-week study 6% had the dose cut from 25 to 10 mg for fasting glucose above 140 mg/dL, and 3 of them still had to stop |
| Plotkin 1997 (abstract, via FDA) | 104 frail adults 65–94; up to 25 mg/day; 9 weeks | Mean fasting glucose up about 8% (5.3 → 5.7 mmol/L) |
| Codner 2001 | 18 GH-deficient children; 7–8 days | No change in glucose or insulin on the higher dose |
| Murphy 2001 | 292 women 64–85; 25 mg/day; 12–18 months | 3 women on MK-677 plus alendronate stopped because of high glucose |
| Bach 2004 | 161 adults 65+ after hip fracture; 25 mg/day; 6 months | Glucose +8.0 mg/dL vs −1.6 on placebo; insulin +2.0 vs −4 µU/mL; HbA1c +0.7% vs +0.3% |
| Nass 2008 | 65 healthy adults 60–81; 25 mg/day; 12 months | Fasting glucose +5 mg/dL; HbA1c +0.2%; insulin sensitivity down; 16 people on MK-677 (vs 2 on placebo) went from normal to 101–110 mg/dL |
| Sevigny 2008 | 563 adults with Alzheimer’s; 25 mg/day; 12 months | Blood glucose raised in 15.4% vs 4.6%; HbA1c raised in 11.1% vs 1.4% |
| Adunsky 2011 | 123 adults 60+ after hip fracture; 25 mg/day; 24 weeks | Raised blood glucose 6.5% vs 1.7%; raised HbA1c 4.8% vs 0% |
Sources: each study as linked, with safety details from the FDA’s 2024 review (FDA 2024).
What these numbers mean
For a fasting glucose test, 99 mg/dL or below is normal, 100 to 125 is prediabetes and 126 or above is type 2 diabetes. For HbA1c, which reflects the last three months, below 5.7% is normal, 5.7% to 6.4% is prediabetes, and 6.5% or above is diabetes (MedlinePlus).
Against those ranges, the 12-month trial looks like this (Nass 2008):
- 16 people on MK-677, and 2 on placebo, went from below 100 mg/dL to 101–110 mg/dL.
- 6 more on MK-677 rose to 110–126 mg/dL.
- After 12 months, 8 people on MK-677 had an HbA1c above 6% (6.1% to 6.4%).
In the earliest trial in older adults, the average fasting glucose after four weeks on 25 mg/day, about 122 mg/dL, was already in the prediabetes range (Chapman 1996). So the average change is small, but it moves a meaningful share of people across a threshold.
Who seemed most affected
- People with more body weight. In the 1996 trial, the glucose rise was linked to body mass index, and the authors suggested people with predisposing risk factors are more likely to develop impaired glucose tolerance (FDA 2024).
- Older adults. Most of the data come from people over 60, who were the main trial population.
- People with existing metabolic problems. Trials excluded people with diabetes (Bach 2004). In a 2022 case report summarized by the FDA, a 47-year-old bodybuilder with prior metabolic syndrome developed a hyperglycemic crisis after adding MK-677 and two SARMs (FDA 2024).
No trial has measured blood sugar effects in young, lean people who train. In obese men aged 18 to 50, fasting glucose stayed the same but the glucose tolerance test got worse (Svensson 1998), which means a normal fasting result doesn’t rule out a change.
Does blood sugar go back to normal after stopping?
In the trials, mostly yes. In the 12-month trial, the glucose changes reversed in people who switched from MK-677 to placebo in year 2, and an 81-year-old man whose fasting glucose and HbA1c rose came back to normal after his dose was cut to 10 mg and he began a low-carbohydrate diet (Nass 2008). In the 8-week trial, one man’s glucose of 10 mmol/L fell back on its own a week later (FDA 2024). Long-term effects after years of use haven’t been studied.
Can MK-677 cause diabetes?
None of the trials summarized by the FDA reported a new diagnosis of diabetes, but none was designed or long enough to answer that. What we know: in the 12-month trial two participants reached fasting glucose of 125–126 mg/dL, right at the diabetes threshold (Nass 2008, MedlinePlus); approved GH medicines warn about diabetes (FDA 2024); and people with diabetes were kept out of the trials (Bach 2004). The FDA counts hyperglycemia among its “serious safety concerns” for ibutamoren (FDA 2024).
What the trials measured and when they acted
- Measured: fasting glucose, HbA1c and fasting insulin, plus an oral glucose tolerance test in one trial (Nass 2008, Svensson 1998).
- Acted: when fasting glucose went above 140 mg/dL, investigators cut the dose from 25 to 10 mg, and stopped treatment if it stayed high (FDA 2024).
This describes how the research was run, not a plan for anyone taking MK-677. Our bloodwork guide and bloodwork planner explain each test, and MK-677 side effects covers the rest of the safety picture. Doses used in the trials are on the MK-677 dosage page.
Frequently asked questions
Does MK-677 raise blood sugar?
Yes, oftenEvidence: Trial
Fasting glucose rose in most MK-677 trials, by 5 mg/dL on average over 12 months. In a 563-patient trial, blood glucose rose in 15.4% of patients vs 4.6% on placebo.
Can MK-677 cause diabetes?
Unknown; not ruled outEvidence: Trial
No trial summarized by the FDA reported a new diabetes diagnosis, but none was designed to answer that. In the 12-month trial, two participants reached fasting glucose of 125 to 126 mg/dL, at the diabetes threshold.
Does MK-677 cause insulin resistance?
Yes, in trialsEvidence: Trial
Insulin sensitivity fell over 12 months in older adults, and insulin rose in GH-deficient men and hip-fracture patients. In obese men an oral glucose tolerance test got worse even though fasting glucose did not change.
Does blood sugar go back to normal after stopping MK-677?
Mostly, in trialsEvidence: Trial
In the 12-month trial the glucose changes reversed in people who switched to placebo. Effects after years of use have not been studied.
How much does MK-677 raise fasting glucose?
Varies by trialEvidence: Trial
About 5 mg/dL on average over 12 months in healthy older adults, and about 8 mg/dL after hip fracture. In the first trial in older adults it rose from about 97 to 122 mg/dL after four weeks.
Sources
- FDA Briefing Document, Pharmacy Compounding Advisory Committee, 29 October 2024: Ibutamoren Mesylate
- Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial
- Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretogogue (MK-677) in healthy elderly subjects
- Oral administration of growth hormone (GH) releasing peptide-mimetic MK-677 stimulates the GH/insulin-like growth factor-I axis in selected GH-deficient adults
- MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism
- Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure
- Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy and functionally impaired elderly adults. The MK-677 Study Group
- Effects of oral administration of ibutamoren mesylate, a nonpeptide growth hormone secretagogue, on the growth hormone-insulin-like growth factor I axis in growth hormone-deficient children
- Effect of alendronate and MK-677 (a growth hormone secretagogue), individually and in combination, on markers of bone turnover and bone mineral density in postmenopausal osteoporotic women
- The effects of MK-0677, an oral growth hormone secretagogue, in patients with hip fracture
- Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial
- MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study
- MedlinePlus: Prediabetes
