1. Blood pyruvate and lactate levels during oral and intravenous glucose tolerance tests are described in obese and non-obese non-diabetic, maturity-onset diabetic and insulin-requiring diabetic groups of women.
2. Mean fasting blood pyruvate levels were similar in non-diabetic, maturity-onset diabetic and insulin-requiring diabetic subjects of similar degree of obesity. Mean levels were higher in the obese groups of non-diabetic and maturity-onset diabetic subjects compared to those of non-obese subjects of similar degree of glucose tolerance.
3. After oral glucose administration similar mean increases of blood pyruvate levels above the fasting base-line were found in non-diabetic and maturity-onset diabetic subjects matched for degree of obesity.
4. Peak oral glucose tolerance test blood pyruvate levels were generally delayed in the maturity-onset diabetic subjects and mean blood pyruvate levels were elevated above those of the non-diabetic subjects during the later stages of the test. Qualitatively similar changes occurred during intravenous glucose tolerance tests.
5. Mean blood lactate/pyruvate ratios were similar in non-obese and obese non-diabetic and maturity-onset diabetic groups of subjects and changed little after oral glucose administration.