Quantitative contributions of gluconeogenesis to glucose production duringfasting in type 2 diabetes mellitus

Contributions of gluconeogenesis to glucose production were determined betw een 14 to 22 hours into a fast in type 2 diabetics (n = 9) and age-weight-m atched controls (n = 7); ages, 60.4 +/- 2.3 versus 55.6 +/- 1.2 years and b ody mass indices (BMI) 28.6 +/- 2.3 versus 26.6 +/- 0.8 kg/m(2). Production was measured using a primed-continuous [6,6-H-2(2)] glucose infusion and g luconeogenesis from H-2 enrichment at carbons 2 and 5 of blood glucose on ( H2O)-H-2 ingestion. plasma glucose concentration declined from 9.6 +/- 0.6 at 14 hours to 7.3 +/- 0.6 at 22 hours in the diabetics (P = .001) and from 5.4 +/- 0.1 to 5.0 +/- 0.1 in the controls (P < .05). Production from the 17(th) to 22(nd) hour declined 27.1% a 0.6% in the diabetics versus 18.5% /- 0.8% in the controls (P = .001); from 10.4 +/- 0.3 to 7.6 +/- 0.2 versus 10.0 +/- 0.4 to 8.2 +/- 0.4 <mu>mol/kg/min. Percent contributions of gluco neogenesis to production measured at 1 1/2- to 2-hour intervals beginning t he 15(th) hour were 6.8% +/- 1.0% more in the 2 diabetics than controls, Th e quantity of glucose contributed by gluconeogenesis declined 19.8% +/- 3.8 % (P < .001) in the diabetics and 6.9% +/- 2.3% in the controls (P = .05); 7.21 +/- 0.32 to 5.74 +/- 0.26 versus 6.20 +/- 0.28 to 5.75 +/- 0.24 <mu>mo l/kg/min. The contribution of glycogenolysis to production, estimated from the difference between production and gluconeogenesis, declined to the same extent in diabetic and control subjects, 40.7% +/- 6.6% and 37.7% +/- 4.1% ; from 3.23 +/- 0.35 to 1.86 +/- 0.26 versus 3.81 +/- 0.22 to 2.42 +/- 0.28 mu mol/kg/min. Thus, gluconeogenesis contributed more to glucose productio n in the diabetic than control subjects. Production and the contribution of gluconeogenesis declined more in the diabetic subjects during the fast. Th e factors regulating these changes remain uncertain. Copyright (C) 2001 by W.B. Saunders Company.