Cyclic Glycine-Proline vs MK-677
Moderate Research vs Well Studied
monitor Mechanism-based · 47% Both Cyclic Glycine-Proline and MK-677 affect insulin sensitivity or blood glucose. Monitor fasting glucose and HbA1c. Consider adding an insulin sensitizer (metformin/berberine).
Molecular Data
Cyclic Glycine-Proline MK-677
Weight 154.17 Da 624.77 Da
Half-life Extended stability (more stable than linear GPE precursor) ~24 hours
Chain 2 amino acids (cyclic) —
Type Cyclic dipeptide (2,5-diketopiperazine) Non-peptide ghrelin receptor agonist
Key Benefits
Cyclic Glycine-Proline
01 Neuroprotection and cognitive enhancement
02 IGF-1 optimization
03 Cardiovascular support
04 Metabolic health improvement
05 Blood-brain barrier penetration
06 Convenient oral administration
MK-677
01 97% increase in 24-hour growth hormone secretion
02 40-72% elevation in IGF-1 levels
03 Enhanced sleep quality with improved REM patterns
04 Preferential lean tissue gains of 1.1-2.7kg over 8-12 months
05 15% basal metabolic rate increase within 2 weeks
06 Oral administration (no injections required)
Side Effects
Cyclic Glycine-Proline
MK-677
Appetite stimulation (>50% of users)
Water retention (30-40%)
Lethargy (20-30%)
Fasting glucose elevation (5-15mg/dL)
Note on testosterone suppression: at doses up to 20 mg daily, MK-677 is unlikely to cause significant testosterone suppression on its own. Above 20 mg daily, the likelihood of suppression and other side effects (insulin resistance, water retention, lethargy) increases. The case report documenting 85.7% testosterone suppression involved co-administration with LGD-4033, a SARM known to be profoundly suppressive, making the SARM the likely primary driver of that suppression.
Contraindications
Consult healthcare provider if taking IGF-1 or growth hormone medications
Limited long-term human data available
Not studied in pregnancy
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
Research Evidence
Cyclic Glycine-Proline MK-677
Status Moderate Research Well Studied
References 4 studies 7 studies
Latest — July 2024
FDA Approved No No
This comparison is for educational and research purposes only. Consult a healthcare professional before use.