Persistent abnormalities of the metabolism of an oral glucose load in insulin-treated type I diabetics.

ABSTRACT

We have compared disposal of an oral glucose load in 12 normal subjects and 10 c-peptide-negative, type I-diabetic subjects, who were treated with insulin (by overnight intravenous insulin infusion followed by a dose of subcutaneous insulin prior to the oral glucose load) to achieve a blood glucose profile that approximated the glucose intolerance commonly seen in insulin-treated diabetics. We used a combination of the dual-isotope and forearm techniques, together with whole-body indirect calorimetry, to quantify the various determinants of glucose tolerance. The diabetic subjects had impaired glucose tolerance in that, despite similar fasting plasma glucose levels (5.46 +/- 0.17 mmol/L v 5.35 +/- 0.10 mmol/L in the normal subjects), they had a higher peak glucose (14.3 +/- 1.2 mmol/L v 10.0 +/- 0.7 mmol/L P less than .01) and area under the glucose curve (2,483 +/- 197 mmol.min/L v 1,525 +/- 43 mmol.min/L P less than .001). Up to 120 minutes after the oral glucose load, the amount of glucose entering the systemic circulation exceeded that leaving by 14.6 +/- 2.3 g in the diabetics and only by 2.6 +/- 0.5 g in the normal subjects (P less than .001), accounting for the higher plasma glucose peak in the diabetics. Total systemic glucose appearance rates were significantly greater in the diabetics between 60 and 120 minutes, and endogenous glucose production suppressed more slowly in diabetics than in the normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)