Context: A better understanding of nocturnal regulation of glucose homeostasis will provide the framework for designing rational therapeutic strategies to improve the management of overnight glucose in patients with type 2 diabetes (T2D).
Objective: To establish the nocturnal pattern and regulation of glucose production (EGP) in humans and to determine whether the pattern is dysregulated in people with T2D.
Design: Subjects were infused with [3-3H] glucose overnight. Arterial blood samples were drawn for hormones and analytes to estimate EGP throughout the night. Deuterium-labeled water was provided to measure gluconeogenesis (GNG) using the hexamethylenetetramine method of Landau.
Setting: Mayo Clinic Clinical Research Trials Unit, Rochester, MN, USA.
Participants and interventions: A total of 43 subjects [23 subjects with T2D and 20 nondiabetic (ND) subjects comparable for age and body mass index] were included in this study.
Main outcome(s) measure(s): Glucose and EGP.
Results: Plasma glucose, C-peptide, and glucagon concentrations were higher throughout the night, whereas insulin concentrations were higher in subjects with T2D vs ND subjects at 1:00 and 4:00 am but similar at 7:00 am. EGP was higher in the subjects with T2D than in the ND subjects throughout the night (P < 0.001). Glycogenolysis (GGL) fell and GNG rose, resulting in significantly higher (P < 0.001) rates of GNG at 4:00 and 7:00 am and significantly (P < 0.001) higher rates of GGL at 1:00, 4:00, and 7:00 am in T2D as compared with ND.
Conclusions: These data imply that optimal therapies for T2D for nocturnal/fasting glucose control should target not only the absolute rates of EGP but also the contributing pathways of GGL and GNG sequentially.