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First-phase insulin secretion: does it exist in real life? Considerations on shape and function.
1Unit of Nutrition and Metabolism, Department of Medicine, San Raffaele Scientific Institute, 20132 Milano, Italy.
American Journal of Physiology. Endocrinology and Metabolism
|August 17, 2004
Summary
The first-phase insulin secretion is crucial for regulating glucose metabolism. This review highlights how the beta-cell
Area of Science:
- Endocrinology
- Metabolic Regulation
- Physiology
Background:
- Insulin secretion's quantitative and dynamic properties are vital for glucose metabolism regulation.
- First-phase insulin secretion plays a key role in optimizing insulin action on target tissues.
Purpose of the Study:
- To review the importance of first-phase insulin secretion in glucose metabolism.
- To illustrate the relationship between intravenous glucose challenge response and early post-ingestion insulin response.
Main Methods:
- Literature data compilation.
- Beta-cell model simulations.
- Analysis of portal-level insulin response dynamics.
Main Results:
- A distinct first-phase insulin release occurs primarily with rapid glucose stimuli (e.g., intravenous).
- Peripheral insulin levels post-glucose ingestion lack a clear biphasic pattern.
- A strong correlation exists between intravenous glucose-induced first-phase insulin response and early post-ingestion insulin response.
Conclusions:
- The beta-cell's capacity for a pronounced first phase correlates with a rapid early insulin increase after glucose ingestion.
- Physiological early insulin response is characterized by a rapidly rising profile, enhanced by incretins and neural signals.
- Portal-level pulsatile insulin release rapidly elevates liver insulin, effectively controlling hepatic glucose production.