In people with type 2 diabetes, tirzepatide lowers fasting glucagon levels more than dulaglutide, which may help reduce excessive glucose release from the liver and improve blood sugar control.
Mechanism
Synthesis from 1 study
Tirzepatide works better than dulaglutide at lowering blood sugar because it turns down the signal that tells the liver to make extra sugar. It does this by hitting two switches on the pancreas’s glucagon-producing cells, which dulaglutide can’t do. Less glucagon means less sugar made by the liver,...
Most probable mechanism
Tirzepatide activates two different receptors on the pancreas's alpha cells, which tells those cells to release less glucagon. With less glucagon in the blood, the liver stops making too much sugar, which helps lower blood sugar levels more than drugs that only activate one receptor.
Tirzepatide binds to both GIP and GLP-1 receptors on pancreatic alpha cells
Receptor activation triggers intracellular signaling that inhibits glucagon secretion
Reduced glucagon levels decrease signaling to the liver to produce glucose via gluconeogenesis and glycogenolysis
Lower hepatic glucose production results in reduced fasting blood glucose levels
Less supported by current evidence, but not ruled out
Tirzepatide helps the body use insulin better, which means the pancreas doesn't need to overproduce insulin or suppress glucagon as much to control blood sugar.
Tirzepatide activates GIP receptors on adipocytes, increasing adiponectin secretion
Increased adiponectin enhances glucose uptake in muscle and fat and reduces liver fat accumulation
Improved insulin sensitivity reduces the need for high insulin output and lowers hyperglucagonemia as a secondary effect
Tirzepatide increases proteins in the blood that help the liver respond better to insulin, which indirectly makes the liver less responsive to glucagon's signal to make sugar.
Tirzepatide upregulates hepatic production of IGFBP-1 and IGFBP-2
Elevated IGFBP-1 and IGFBP-2 alter IGF-1 bioavailability and enhance insulin signaling in hepatocytes
Improved hepatic insulin sensitivity dampens the liver's response to glucagon, reducing glucose production
Evidence from Studies
Supporting (1)
Community contributions welcome
Dual GIP and GLP-1 Receptor Agonist Tirzepatide Improves Beta-cell Function and Insulin Sensitivity in Type 2 Diabetes
Contradicting (0)
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