Muscle glucose transport and phosphorylation in type 2 diabetic, obese nondiabetic, and genetically predisposed individuals

Merri Pendergrass, Alessandra Bertoldo, Riccardo Bonadonna, Gianluca Nucci, Lawrence Mandarino, Claudio Cobelli, Ralph A. DeFronzo

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

Our objectives were to quantitate insulin-stimulated inward glucose transport and glucose phosphorylation in forearm muscle in lean and obese nondiabetic subjects, in lean and obese type 2 diabetic (T2DM) subjects, and in normal glucose-tolerant, insulin-resistant offspring of two T2DM parents. Subjects received a euglycemic insulin (40 mU·m -2·min-1) clamp with brachial artery/deep forearm vein catheterization. After 120 min of hyperinsulinemia, a bolus of D-mannitol/3-O-methyl-D-[14C]glucose/D-[3-3H]glucose (triple-tracer technique) was given into brachial artery and deep vein samples obtained every 12-30 s for 15 min. Insulin-stimulated forearm glucose uptake (FGU) and whole body glucose metabolism (M) were reduced by 40-50% in obese nondiabetic, lean T2DM, and obese T2DM subjects (all P < 0.01); in offspring, the reduction in FGU and M was ∼30% (P < 0.05). Inward glucose transport and glucose phosphorylation were decreased by ∼40-50% (P < 0.01) in obese nondiabetic and T2DM groups and closely paralleled the decrease in FGU. The intracellular glucose concentration in the space accessible to glucose was significantly greater in obese nondiabetic, lean T2DM, obese T2DM, and offspring compared with lean controls. We conclude that 1) obese nondiabetic, lean T2DM, and offspring manifest moderate-to-severe muscle insulin resistance (FGU and M) and decreased insulin-stimulated glucose transport and glucose phosphorylation in forearm muscle; these defects in insulin action are not further reduced by the combination of obesity plus T2DM; and 2) the increase in intracelullar glucose concentration under hyperinsulinemic euglycemic conditions in obese and T2DM groups suggests that the defect in glucose phosphorylation exceeds the defect in glucose transport.

Original languageEnglish (US)
Pages (from-to)E92-E100
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume292
Issue number1
DOIs
StatePublished - Jan 2007

Keywords

  • Glucose phosphorylation
  • Insulin resistance
  • Muscle
  • Obesity
  • Type 2 diabetes

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

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