Aims/Introduction
To evaluate the contribution of pancreatic α‐cell function to the dawn phenomenon, insulin sensitivity, hepatic glucose uptake and glycemic variability in patients with type 1 diabetes.
Materials and Methods
In 40 patients with type 1 diabetes, arginine stimulation tests were carried out, and the area under the curve (AUC) of glucagon was measured using radioimmunoassays (
AUC
glc
RIA
) and enzyme‐linked immunosorbent assays (
AUC
glc
ELISA
). The ratio of the insulin dose delivered by an artificial pancreas to maintain euglycemia between 04.00 and 08.00 hours or between 00.00 and 04.00 hours was measured as the dawn index. The glucose infusion rate and
hepatic glucose uptake
were measured using hyperinsulinemic euglycemic clamp and clamp oral glucose loading tests. Glycemic variability in 96 h was measured by continuous glucose monitoring.
Results
The median dawn index (1.7, interquartile range 1.0–2.8) was not correlated with
AUC
glc
RIA
(
R
2
= 0.03,
P
=
0.39) or
AUC
glc
ELISA
(
R
2
= 0.04,
P
=
0.32). The median
glucose infusion rate
(7.3 mg/kg/min, interquartile range 6.4–9.2 mg/kg/min) was significantly correlated with
AUC
glc
RIA
(
R
2
= 0.20,
P
=
0.02) and
AUC
glc
ELISA
(
R
2
= 0.21,
P
=
0.02). The median
hepatic glucose uptake
(65.3%, interquartile range 40.0–87.3%) was not correlated with
AUC
glc
RIA
(
R
2
= 0.07,
P
=
0.26) or
AUC
glc
ELISA
(
R
2
= 0.26,
P
=
0.79). The standard deviation of glucose levels measured by
continuous glucose monitoring
was significantly correlated with
AUC
glc
RIA
(
R
2
= 0.11,
P
=
0.049), but not with
AUC
glc
ELISA
(
R
2
= 0.01,
P
...