Effect of Overnight Restoration of Euglycemia on Glucose Effectiveness in Type 2 Diabetes Mellitus1

The ability of glucose to stimulate its own uptake and suppress its own release is impaired in type 2 diabetes. To determine whether glucose effectiveness is improved by short term euglycemia, 10 type 2 diabetic subjects were studied on 2 occasions. Insulin was infused throughout the night to maintain euglycemia (approximately 5 mmol/L), or glucose was permitted to remain at ambient hyperglycemic levels (approximately 10 mmol/L) until the following morning when euglycemia was achieved with a variable insulin infusion. A prandial glucose infusion (containing 35 g glucose) was started at 1000 h, and the variable insulin infusion was replaced by a constant infusion of insulin (0.25 mU/ kg x min), somatostatin (60 ng/kg x min), glucagon (0.65 ng/kg x min), and GH (3 ng/kg x min) to maintain hormone concentrations at constant basal levels. Although nocturnal glucose concentrations were (by design) higher (P<0.01) on the hyperglycemic than on the euglycemic study day (10.1+/-0.2 vs. 5.4+/-0.1 mmol/L), glucose concentrations did not differ either before (4.9+/-0.1 vs. 4.9+/-0.1 mmol/L) or during the prandial glucose infusion (peak, 11.1+/-0.5 vs. 11.3+/-0.5 mmol/L; incremental area, 1390+/-254 vs. 1409+/-196 mmol/L x 6 h). Furthermore, glucose-induced stimulation of glucose disappearance (2068+/-218 vs. 1957+/-244 micromol/kg x 6 h) and suppression of glucose production (-2253+/-378 vs. -2124+/-257 micromol/kg x 6 h) did not differ. Thus, restoration of euglycemia by means of an overnight insulin infusion does not alter glucose effectiveness in people with type 2 diabetes.