title: Effects of acute pinitol supplementation on plasma pinitol concentration, whole body glucose tolerance, and activation of the skeletal muscle insulin receptor in older humans.
abstract: Limited research with rodents and humans suggests that oral ingestion of pinitol (3- O-methyl- D- CHIRO-inositol) might positively influence glucose tolerance. This double-blinded, placebo-controlled, and cross-over study assessed the effects of acute pinitol supplementation on plasma pinitol concentration, glucose tolerance, insulin sensitivity, and activation of the skeletal muscle insulin receptor. Fifteen older, nondiabetic subjects (62+/-1 years, mean+/-SEM) completed four, 1-day trials. Subjects consumed a non-nutritive beverage with nothing (placebo) or 1,000 mg pinitol. Sixty minutes later, the subjects consumed beverages that were either energy- and carbohydrate-free (Sham) or contained 75 g glucose (OGTT). Blood samples were collected frequently over the 240-min testing period. For the OGTT trials only, vastus lateralis samples were obtained before the placebo and pinitol supplementation and 60 min after consuming the 75 g glucose beverage. Plasma pinitol concentration increased and was maintained for 240 min. Pinitol did not influence the fasting state and 180-min area under the curves for plasma glucose and insulin during the Sham and OGTT trials or hepatic (placebo 0.83+/-0.08; pinitol 0.80+/-0.08) and whole-body (placebo 6.10+/-0.54; pinitol 6.22+/-0.52) insulin sensitivities. Activation of the muscle insulin receptor was increased by 140% with glucose ingestion (Pre 0.62+/-0.12; Post 1.49+/-0.35), but pinitol did not influence this response. These results show that the pinitol supplement was quickly absorbed, but did not acutely influence indices of whole-body glucose tolerance and insulin sensitivity, or the activation of the skeletal muscle insulin receptor in older, nondiabetic humans.
authors.affiliation: Department of Foods and Nutrition and Center on Aging and the Life Course, Purdue University, West Lafayette, IN 47907-2059, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Stull
authors.forename: K V
authors.initials: KV
authors.lastname: Wood
authors.forename: J P
authors.initials: JP
authors.lastname: Thyfault
authors.forename: W W
authors.initials: WW
authors.lastname: Campbell
mesh_terms: D000368:Aged; D001786:Blood Glucose / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005947:Glucose / Q000378:metabolism; D005951:Glucose Tolerance Test; D006801:Humans; D007294:Inositol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D010766:Phosphorylation; D011972:Receptor, Insulin / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D007328:Insulin; C021730:pinitol; D007294:Inositol; D011972:Receptor, Insulin; D005947:Glucose