PROBLEM TO BE SOLVED: To provide a therapeutic method for diseases influencing on glucose metabolism, such as Type II diabetes.SOLUTION: There is provided a method for promoting proliferation of pancreatic cells by making pancreatic cells contact with a composition containing peptide YY (PYY) or its agonist. It can be achieved by administering the PYY peptide or a PYY agonist drug having PYY activity to pancreatic islets or isolated &bgr;-cells.【課題】グルコース代謝に影響する、II型糖尿病のような疾患に対する治療法を提供する。【解決手段】膵島又は単離β細胞に、PYY活性のPYYペプチド又はPYY作用薬を投与する【選択図】図1