Postprandial changes in plasma ketone body and carnitine levels in normal and non-insulin-dependent diabetic subjects

We have examined changes in plasma ketone bodies and their related metabolites after the ingestion of a mixed meal in normal and NIDDM (non-insulin-dependent diabetes mellitus) using a highly sensitive colorimetric method. In normal subjects, fasting plasma acetoacetic acid (AcAc) and 3-beta-hydroxybutyric acid (3-OHB) concentrations were 40.2 +/- 2.9 and 21.3 +/- 4.0 microM, respectively. The total carnitine level in fasting plasma was 48.2 +/- 3.2 microM and acyl/free was 0.34 +/- 0.12. These values did not change significantly after the meal. In diabetic subjects, fasting AcAc and 3-OHB levels were 57.9 +/- 3.5 and 97.9 +/- 14.7 microM, respectively and these values especially 3-OHB, decreased almost to the normal level by 4 h after the meal. The total carnitine level in the fasting plasma of diabetics was 48.7 +/- 2.8 microM and acyl/free was 0.58 +/- 0.09. Such characteristics were observed when their plasma glucose had been completely normal for more than 10 days. In patients treated with sulfonylurea, the fasting ketone body level, especially 3-OHB, was significantly lower than that of diabetics treated with insulin or diet alone, whereas the fasting plasma glucose level and its postprandial increase were higher than those of the others. These results demonstrate that measurement of the plasma ketone body (especially 3-OHB) level is a sensitive tool for monitoring the metabolic status of NIDDM.