Animal experiment:

Rats[1]To test the effect of miniglucagon (Glucagon (19-29)) on stimulated insulin secretion, 8.3 mM glucose is perfused during the experiments, including a 45-min equilibration period, followed by miniglucagon (1, 10, 100, and 1,000 pM) perfused with or without 1 nM tGLP-1. To study the glucagon and miniglucagon secretion, the glucose concentration is switched from 11 to 3 mM after a 45-min stabilization period, and the peptides secreted are measured by radioimmunoassay[1].

Glucagon(NH₂-His-Ser-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Lys-Tyr-Leu-Asp-Ser-Arg-Arg-Ala-Gln-Asp-Phe-Val-Gln-Trp-Leu-Met-Asn-Thr-COOH) is a peptide hormone, secreted by the pancreas, that raises blood glucose levels. Glucagon’s effect is opposite that of insulin, which lowers blood glucose levels. Miniglucagon (Glucagon 19–29) is a potent and efficient inhibitor of secretagogue-induced insulin release through a Ca²⁺Pathway*. Miniglucagon is a novel local regulator of the pancreatic islet physiology. Any abnormal inhibitory tone exerted by this peptide on the β-cell results in impaired insulin secretion, as observed in type 2 diabetes. Miniglucagon is a component of the positive inotropic effect of glucagon. Some evidence has shown that glucagon processing into miniglucagon may be essential for the positive inotropic effect of glucagon on heart contraction.

References:
1. Reece J, Campbell N (2002). Biology. San Francisco: Benjamin Cummings. ISBN 0-8053-6624-5.
2. Stéphane Dalle, Ghislaine Fontés, Anne-Dominique Lajoix2, Laurence LeBrigand, René Gross, Gérard Ribes, Michel Dufour, Léo Barry, Dung LeNguyen and Dominique Bataille, Miniglucagon (Glucagon 19-29) A Novel Regulator of the Pancreatic Islet Physiology, doi:10.2337/diabetes.51.2.406Diabetes February 2002 vol. 51 no. 2406-412
3. Pavoine C, Brechler V, Kervan A, Blache Kervan, Le-Nguyen D, Laurent S, Bataille D, Pecker F (1991) Miniglucagon [glucagon-(19-29)] is a component of the positive inotropic effect of glucagon. Am J Physiol 260:C993–C999.