Dysregulation of
glucagon secretion plays an important role in the pathogenesis of
type 2 diabetes (T2DM). However it hasn't been elucidated involvement of
glucagon dysregulation in pathophysiology of T2DM. Recently a new
glucagon sandwich
enzyme-linked
immunosorbent assay (ELISA) became available that can measure plasma
glucagon level with higher accuracy and simpler procedure than the conventional RIA method. We performed OGTT for adult subjects aged 20-69 years to define normal
glucose tolerance (NGT, n = 25), borderline
glucose intolerance (defined as pre-
diabetes mellitus: preDM, n = 15), or
diabetes mellitus (DM, n = 13), and we measured
glucagon levels with this new ELISA method at fasting and during OGTT. Plasma
glucose,
insulin,
glucagon and active
GLP-1 were also measured. This study took place in diabetes outpatient clinic in Kitasato University Hospital and an affiliated outpatient clinic. PreDM and DM exhibited higher fasting plasma
glucagon levels than NGT (34.4 ± 4.6 and 44.1 ± 5.0 vs. 20.6 ± 3.6 pg/mL), and statistical significance was observed between NGT and DM (p < 0.05). There was significant correlation between fasting
glucagon level and indexes of
insulin sensitivity. During OGTT,
glucagon levels were less suppressed in DM and preDM than in NGT, whereas no apparent relationship was observed between
glucagon and
GLP-1 secretion. Significant positive correlation was observed between
glucagon levels during OGTT and fasting TG. In conclusion, subjects with mild T2DM exhibited fasting hyperglucagonemia and insufficient suppression to oral
glucose load compared to NGT subjects.