PROBLEM TO BE SOLVED: To provide an insulin secretagogue which is effective in preventing diabetes and the like and which is very safe and free of concern of side effects even when ingested continuously.SOLUTION: This insulin secretagogue contains, as an active ingredient, an HLB-4 to 15 polyglycerin fatty acid ester, and is therefore very safe and free of concern of side effects even when ingested continuously. It is preferable that the insulin secretagogue contains glycerin fatty acid ester along with fat and oil. Alternatively the insulin secretagogue may be used along with fat and oil.