Insulins and Biguanides — Role in Performance Protocols Insulin is the most anabolic hormone in the body — it drives nutrient uptake into muscle cells, increases protein synthesis and inhibits catabolism. Biguanides like Metformin improve insulin sensitivity — making the body's existing insulin more effective, improving glucose disposal and reducing insulin resistance caused by HGH protocols. Sulfonylureas like Glimepiride stimulate pancreatic insulin secretion directly for more active glucose management. Metformin — The Primary Biguanide Metformin (Glucophage) is the most widely used biguanide — a first-line diabetes medication with a strong evidence base for insulin sensitisation and metabolic health. In performance contexts it is primarily used for: HGH protocol support: exogenous GH elevates blood glucose and causes insulin resistance — Metformin mitigates this effect, allowing higher GH doses with better glucose management General metabolic health: reduces fasting glucose, improves insulin sensitivity and activates AMPK — a key metabolic regulator Longevity protocols: low-dose Metformin is studied for anti-aging properties through AMPK activation and mTOR pathway modulation Standard performance dose: 500–1000 mg/day with meals. Always taper up from 500 mg/day to avoid gastrointestinal side effects — the most common complaint with Metformin. Glimepiride — Sulfonylurea Amaryl (Glimepiride) is a third-generation sulfonylurea that stimulates pancreatic beta cells to secrete insulin — a different and more direct mechanism than Metformin. Where Metformin improves sensitivity to existing insulin, Glimepiride increases insulin output. Used for type 2 diabetes management and glucose control where biguanide support alone is insufficient. Requires careful dosing to avoid hypoglycaemia — blood glucose monitoring is essential. Related categories: for additional glucose control compounds see the Pharmacy category. For GH protocols that require insulin management see HGH & Hormone Sets. For weight loss and metabolic compounds see Weight Loss. Frequently Asked Questions Why do bodybuilders use Metformin? ＋ Primarily alongside HGH protocols — exogenous GH causes insulin resistance and elevated blood glucose, and Metformin mitigates this effect. Also used for general insulin sensitisation on high-calorie bulking protocols and as a longevity compound for its AMPK activation. Not a fat burner — its value is metabolic health and insulin sensitivity improvement. Is Metformin safe to use on a steroid cycle? ＋ Yes — Metformin does not interact with AAS pharmacology. It does not affect testosterone, estrogen or the HPG axis. Its primary interaction to be aware of is with alcohol — combining Metformin and heavy alcohol use increases lactic acidosis risk. Start at 500 mg/day with food and titrate up to avoid GI side effects which are the most common complaint. What is the difference between Metformin and Glimepiride? ＋ Different mechanisms for the same goal — glucose control. Metformin (biguanide) improves insulin sensitivity and reduces hepatic glucose output without stimulating insulin secretion — lower hypoglycaemia risk. Glimepiride (sulfonylurea) stimulates the pancreas to produce more insulin directly — more potent glucose reduction but requires careful dosing to avoid hypoglycaemia. They are often combined in clinical diabetes management for complementary effect. What is the difference between Metformin and insulin? ＋ Insulin is the hormone itself — injected to drive nutrients directly into cells. Exogenous insulin use in bodybuilding carries serious hypoglycaemia risk and is an advanced-only protocol. Metformin is an insulin sensitiser — it makes the body's own insulin more effective without directly lowering blood sugar. Metformin is significantly safer and more accessible; exogenous insulin requires expert knowledge and carries genuine life-threatening risk if misused.