Comparison of Insulin Action on Glucose versus Potassium Uptake in Humans

Abstract

SummaryBackground and objectives Insulin has several physiologic actions that include stimulation of cellular glucose and potassium uptake. The ability of insulin to induce glucose uptake by cells is impaired in type 2 diabetes mellitus, but whether potassium uptake is similarly impaired is not known. This study examines whether the cellular uptake of these molecules is regulated in concert or independently.Design, setting, participants, & measurements Thirty-two nondiabetic and 13 type 2 diabetic subjects with normal GFR were given a similar, constant metabolic diet for 8 days. On day 9, they were subjected to a hyperinsulinemic euglycemic clamp for 2 hours. Serum and urinary chemistry were obtained before and during the clamp. Glucose disposal rate was calculated from glucose infusion rate during hyperinsulinemic euglycemia. Intracellular potassium and phosphate uptake were calculated by the reduction of extracellular potassium or phosphate content corrected for urinary excretion.Results Although glucose disposal rate tended to be lower in type 2 diabetics, cellular potassium uptake was similar between diabetics and nondiabetics. Additionally, although glucose disposal rate was lower with increasing body mass index (R 2 ϭ 0.362), cellular potassium (R 2 ϭ 0.052), and phosphate (R 2 ϭ 0.002), uptake rates did not correlate with body mass index. There was also no correlation between glucose disposal rate and potassium (R 2 ϭ 0.016) or phosphate uptake (R 2 ϭ 0.053).Conclusions Insulin-stimulated intracellular uptake of glucose and potassium are independent of each other. In type 2 diabetes, potassium uptake is preserved despite impaired glucose disposal.

Regulation of Potassium Homeostasis

“…An increase in the activity of the Na (Figure 1). In patients with the metabolic syndrome or CKD, insulin-mediated glucose uptake is impaired, but cellular K 1 uptake remains normal (4,5), demonstrating differential regulation of insulin-mediated glucose and K 1 uptake.…”

Experience using high-dose glucose-insulin-potassium (GIK) in critically ill patients

“…As we found, higher glucose dosing would be required as insulin causes a net intracellular shift [44].…”

Cardioprotective Effects of Insulin

“…14 The enhancement of K ϩ uptake into tissues by insulin occurs independent of glucose uptake, and the rate of K ϩ uptake in diabetic subjects has been shown to be similar to that in healthy control subjects. 106 However, a separate meta-analysis investigating the effect of perioperative GIK infusion on mortality and AF after coronary artery bypass grafting found no significant reduction in AF by perioperative GIK infusion, 36 and insulin cardioplegia did not decrease the incidence of postoperative arrhythmias compared with placebo in another study. 107 …”