It is intended to provide a noninvasive method of conveniently detecting
mild impaired glucose tolerance and/or insulin hyposecretion at the early
stage with the use of an enzyme. Namely, mild impaired glucose tolerance
and/or hyposecretion at the early stage are detected by quantifying
myoinositol secreted into the urine before loading glucose and after
loading glucose for a definite period of time with the use of a reagent
and comparing the increase (or the increase ratio) in the myoinositol
content thus measured with a characteristic level which has been
preliminarily determined in normal subjects.