Frequency of diabetes mellitus in patients with Klinefelter's syndrome of different chromosome constitutions and the XYY syndrome. Plasma insulin and growth hormone level after a glucose load.

Abstract

Glucose tolerance and plasma insulin and growth hormone response to a glucose load have been studied in 31 patients with chromatin-positive Klinefelter's syndrome with different sex chromosome constitution, 8 with chromatin-negative Klinefelter's syndrome, and 6 with the XYY syndrome. We found that 39% of patients with chromatin-positive Klinefelter's syndrome had a diabetic GTT; 19% of their mothers had overt diabetes mellitus. These frequencies are significantly higher than expected. One of the 8 patients with chromatin-negative Klinefelter's syndrome and none of the 6 patients with the XYY syndrome had a diabetic GTT. The diabetes in patients with Klinefelter's syndrome was of a mild type, as is most often found in diabetes of maturity-onset type. The insulin response was, however, different from what is usually found in maturity-onset diabetes. The patients with Klinefelter's syndrome had a brisk rise of plasma insulin and prolonged high levels after glucose ingestion. The inability of endogenous insulin to decrease the blood sugar level was not due to elevated plasma growth hormone. However, there was a peak plasma growth hormone at 2, 2½ and 3 hr in 8 of 23 patients with chromatin-positive Klinefelter's syndrome. The etiology and pathogenesis of the mild diabetes in patients with chromatin-positive Klinefelter's syndrome are discussed.