Follow-up of "non-diabetic" relatives of diabetics by retesting oral glucose tolerance after 5 years.

Of 743 first degree relatives of diabetics in whom oral glucose tolerance tests had been performed in 1967 488 were re-tested in 1972. Among the original "normals" (n = 353) 17.6% had developed a "subclinical" and 1.3% an "overt diabetes" within 5 years. The original "subclinical diabetes" (n = 118) showed a remission to "normal" in 35.6% and a progression to "overt diabetes" in 13.6%. 3 out of the 17 formerly "overt diabetes" were found to be "normal" after 5 years and 3 were "subclinical diabetics". Thus the performance of an oral glucose tolerance test is of limited prognostic value in the individual case. In both studies a higher prevalence of abnormal test results occurred in the older age groups and in overweight subjects. Remission or deterioration did not depend, however, on age or on weight changes. The frequency of abnormal tests was higher in males than in females, but the tendency towards the development of diabetes was more pronounced in females, in accordance with a previous observation of a higher age dependance of glucose tolerance in females.