First phase of insulin release

Glucose-induced stimulahon of insulin release from cells is biphasic. The initial rapid rise in insulin that follows a rise in glucose is termed the first phase of insulin release and is thought to reflect the release of the presynthesized insulin in the storage granules a more... 

This is a combination of a proportional control (first term of the parentheses) and a differential (second term). The beta cell is thus able to respond with a fast, but transient, response dependent on the rate of glucose change. This is demonstrated in Fig. 6.5b, where the glucose concentration increases from 5 mM to 10 mM as a logistic function with different slopes. The figure shows that there is an increasing overshoot for increasing slope. This type of differential control explains part of the so-called first phase of insulin release [33-35]. 

The IVGTT, where a bolus of glucose is administered intravenously, is mostly used to test the first phase of insulin release and the insulin sensitivity of glucose uptake. 

Microspheres of the biodegradable, triblock copol3rmer (PLGA-PEG-PLGA, Mw = 4000, 1500-1000-1500 by NMR) were prepared in two methods microsphere A (Msp A aqueous-based) and microsphere B (Msp B dichloromethane). For both microspheres, an equal amoxmt of Zn-insiilin was loaded ( 4% of pol3nner mass). In vitro release studies were carried out with both. As shown in Fig. 6, Msp A exhibited a continuous and nearly complete release of insiilin over 3 weeks. The first phase of insulin release (the first 10 days) from Msp A seems to be dependent more upon diffusion, indicated by the slight decrease in the release rate over time. Then, after day 10, the insulin release rate turned to an... 

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See also in sourсe #XX -- [ ]

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