TABLE 2.
Actions of GIP and GLP-1 that affect blood glucose levels
| GIP | GLP-1 | |
|---|---|---|
| Islets | ||
| Insulin secretion | ↑ | ↑ |
| Insulin synthesis | ↑ | ↑ |
| Insulin, glucokinase and GLUT2 expression | ↑ | ↑ |
| Glucagon secretion | ↑ | ↓ (indirect) |
| Somatostatin secretion | ↑ | ↑ (indirect) |
| β cell proliferation | ↑ | ↑ |
| β cell apoptosis | ↓ | ↓ |
| Sweet taste modulator | — | Yes |
| Gastrointestinal tract | ||
| Gastric emptying | — | ↓ |
| Gastric acid secretion | ↓ | ↓ |
| Motility | — | ↓ |
| Central nervous system | ||
| Food intake | — | ↓ |
| Satiety | — | ↑ |
| Muscle | ||
| Glucose uptake | — | ↑ |
| Liver | ||
| Glucose production | ↓ (indirect) |
↓ (indirect) |
↑, increase; ↓, decrease; —, no effect or not reported.