An object of the present invention is to confirm the safety of a fermented papaya preparation in type 2 diabetic patients while determining its effect on ATP production and mitochondria to find further health advantages for type 2 diabetic patients. The present invention provides an ATP production promoter for promoting ATP production in type 2 diabetic patients and a mitochondrial activity promoter for promoting mitochondrial activity in the patients, each comprising a fermented papaya product as an active ingredient. The present invention also provides an immunostimulant for type 2 diabetic patients, based on promoting ATP production and/or mitochondrial activity in type 2 diabetic patients, comprising a fermented papaya preparation as an active ingredient.
