Steady-State Brain Glucose Concentrations During Hypoglycemia in Healthy Humans and Patients With Type 1 Diabetes

• Published in: Diabetes (New York, N.Y.) Vol. 61; no. 8; pp. 1974 - 1977
• Main Authors: DE VEN, Kim C. C. Van, DER GRAAF, Marinette Van, TACK, Cees J, HEERSCHAP, Arend, DE GALAN, Bastiaan E
• Format: Journal Article
• Language: English
• Published: Alexandria, VA American Diabetes Association 01.08.2012
• Subjects: Adult; Analysis; Biological and medical sciences; Blood Glucose - metabolism; Blood-brain barrier; Blood-Brain Barrier - metabolism; Brain - metabolism; Complications and side effects; Diabetes; Diabetes Mellitus, Type 1 - metabolism; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Female; Genetic aspects; Glucose; Glucose - metabolism; Glucose Clamp Technique; Humans; Hypoglycemia; Hypoglycemia - metabolism; Kinetics; Magnetic Resonance Spectroscopy; Male; Medical research; Medical sciences; Metabolism; NMR; Nuclear magnetic resonance; Physiological aspects; Plasma; Spectrum analysis; Type 1 diabetes; Netherlands; Endocrinopathy; Human; Immunopathology; Type 1 diabetes; Central nervous system; Autoimmune disease; Metabolic diseases; Glucose; Hypoglycemia; Encephalon
• ISSN: 0012-1797; 1939-327X
• DOI: 10.2337/db11-1778

The objective of this study was to investigate the relationship between plasma and brain glucose levels during euglycemia and hypoglycemia in healthy subjects and patients with type 1 diabetes mellitus (T1DM). Hyperinsulinemic euglycemic (5 mmol/L) and hypoglycemic (3 mmol/L) [1-(13)C]glucose clamps were performed in eight healthy subjects and nine patients with uncomplicated T1DM (HbA(1c) 7.7 ± 1.4%). Brain glucose levels were measured by (13)C magnetic resonance spectroscopy. Linear regression analysis was used to fit the relationship between plasma and brain glucose levels and calculate reversible Michaelis-Menten (MM) kinetic parameters. Brain glucose values during euglycemia (1.1 ± 0.4 μmol/g vs. 1.1 ± 0.3 μmol/g; P = 0.95) and hypoglycemia (0.5 ± 0.2 μmol/g vs. 0.6 ± 0.3 μmol/g; P = 0.52) were comparable between healthy subjects and T1DM patients. MM kinetic parameters of combined data were calculated to be maximum transport rate/cerebral metabolic rate of glucose (T(max)/CMR(glc)) = 2.25 ± 0.32 and substrate concentration at half maximal transport (K(t)) = 1.53 ± 0.88 mmol/L, which is in line with previously published data obtained under hyperglycemic conditions. In conclusion, the linear MM relationship between plasma and brain glucose can be extended to low plasma glucose levels. We found no evidence that the plasma to brain glucose relationship or the kinetics describing glucose transport over the blood-brain barrier differ between healthy subjects and patients with uncomplicated, reasonably well-controlled T1DM.