Effect of dexamethasone on oral glucose tolerance in healthy adults.
ABSTRACT To determine the dose-response and time course of action of a single dose of dexamethasone on plasma glucose and insulin dynamics in healthy adults.
Participants included healthy adults who met the following inclusion criteria: 18 to 65 years of age, body mass index of 18 to 25 kg/m2, no family history of diabetes mellitus, not taking any medication known to affect glucose tolerance, and nonpregnant state for female participants. Each participant underwent 3 sequential blocks of 75-g oral glucose tolerance tests (OGTTs) on days 1, 2, and 3; this sequence was repeated on 3 different occasions separated by more than 2 weeks. On the first day of each block, participants reported to the research center after a 10- to 12-hour overnight fast, and fasting baseline blood samples for glucose, insulin, and C-peptide were obtained. Baseline (0 mg) OGTT was then performed with a 75-g glucose load, and blood samples were collected at 30, 60, 90, and 120 minutes for measurements of glucose, insulin, and C-peptide. After the baseline OGTT on day 1, a single dose of either 2-, 4- or 8-mg of dexamethasone was administered orally. Twenty-four and 48 hours later, participants returned for additional OGTTs.
Ten healthy volunteers (4 male and 6 female) were enrolled. The effect of dexamethasone was maximal 24 hours after 8-mg dexamethasone compared with the effect observed after no dexamethasone administration. At 60 minutes during the OGTT (following 8-mg dexamethasone), blood glucose increased from 127 ± 7.1 mg/dL (6.35 ± 0.36 mmol/L) to 176 ± 19 mg/dL (8.8 ± 0.95 mmol/L), insulin increased from 49.3 ± 3.2 μIU/mL (342 ± 22 pmol/L) to 119.7 ± 10.1 μIU/mL (831 ± 70 pmol/L), and C-peptide increased from 6376 ± 510 pg/L (1913 ± 153 pmol/L) to 10 143 ± 1016 pg/L (3043 ± 305 pmol/L); the 60-minute levels returned towards baseline at 48 hours. Smaller changes were observed with 2- and 4-mg dexamethasone. Twenty-four hours after 8-mg dexamethasone, there was a 2.2- and 1.5-fold increase in homeostasis model assessment of insulin resistance and homeostasis model assessment of β cells, respectively, and a 2.5-fold decrease in the Matsuda sensitivity index.
A single oral dose of 8-mg dexamethasone increases blood glucose, insulin, and C-peptide levels maximally at 24 hours, 1 hour following 75-g OGTT. A dexamethasone stress test might identify persons at increased risk for type 2 diabetes.
Article: Effect of dexamethasone on glucose homeostasis in normal and prediabetic individuals with a first-degree relative with type 2 diabetes.[show abstract] [hide abstract]
ABSTRACT: Objective We determined the effect of a single 8 mg oral dose of DEX or placebo on glucose and insulin homeostasis, during OGTTs performed before and 24 h after DEX. Experiments were conducted in normal glucose tolerant (NGT) and prediabetic individuals, all of whom had at least one first-degree relative with type 2 diabetes.Methods This was randomized, double-blind, placebo-controlled study. Measures of glucose and insulin homeostasis derived from OGTTs before and 24 h after DEX or placebo were compared in 21 placebo-treated versus 23 DEX-treated individuals with NGT, and in 23 placebo-treated versus 20 DEX-treated prediabetic individuals.Results Before DEX or placebo, area under-the-curve for glucose [AUC(g)] and HOMA-IR were higher, and Matsuda and disposition indices were lower in prediabetic compared to the NGT group. In both NGT and prediabetic groups treated with DEX, glucose and insulin at fasting and during OGTT were increased compared with placebo-treated groups at 24 h (p= 0.001). DEX treatment in both groups increased HOMA-IR and AUC(g) and decreased Matsuda index (p= 0.001). No significant changes were observed in AUC(i)/AUC(g) or HOMA-B after DEX in either the NGT or prediabetic groups. Disposition index (DI) decreased and was lowest in the prediabetic group after DEX.Conclusion In a population in which all subjects had at least one first-degree relative with type 2 diabetes, individuals with prediabetes are more insulin resistant and have lower DI compared to persons with NGT. Prediabetic individuals also show a marked decrease in DI when challenged with a single 8 mg oral dose of DEX.Endocrine Practice 07/2012; · 2.49 Impact Factor