Effects of different forms and dosage of glucose on results of oral glucose tolerance test
Authors: Jin Cui, Hong-yan Wei, Ming-cai Qiu
Journal: BMJ (2011)

Objective To investigate feasibility of use of glucose injection instead of glucose powder in oral glucose tolerance test (OGTT). Methods Sixty healthy adult volunteers without history of diabetes were recruited for a standard OGTT with 75 g anhydrous glucose powder first. One week later, they were randomly divided into two groups, each of the one group (30 volunteers) orally took seven ampoules (20 ml/ampoule) and each of the other group (30 volunteer) took 7.5 ampoules of 50％ glucose injection for OGTT again, as compared to those with standard OGTT. Plasma levels of glucose and insulin were examined to evaluate whether different forms and dosage of glucose had similar results in OGTT. Results In 23 volunteers with normal glucose tolerance, their plasma levels of glucose were ( 4. 8 ± 0. 4 ), ( 6. 7 ±0. 6), (5.9 ±0. 8), (5.5 ±0. 9) and (4. 8 ±0. 9) mmol/L at 0, 30, 60, 120 and 180 min after oral load with 75 g anhydrous glucose powder, respectively. These values changed to (4. 8 ± 0. 3 ), (7.5 ± 1.1 ),(6.8±1.8), (6.3 ±1.0) and (4.6 ±1.2) mmol/Lor (4.7 ±0.3), (7.2±1.3), (6.1 ±1.1),(5.6 ± 0. 9 ) and (4. 3 ± 0. 9) mmol/L after oral load with seven ampoules ( 15 volunteers) or 7. 5 ampoules of (8 volunteers ) of 50％ glucose injection, respectively. With standard OGTT, 37 cases of impaired glucose tolerance were found from 60 volunteers tested, and their plasma levels of glucose were (5. 2 ±0.6), (9. 1 ±1.4), (8.9 ±2.6), (6.7±2.0) and (4.7 ±1.0) mmol/L at 0, 30, 60, 120 and 180 min after oral load with 75 g anhydrous glucose powder, respectively; (5. 1 ± 0. 7 ), ( 8. 8 ± 1. 7 ), (9. 0 ±3.0), (7.3±2.2) and (5.1 ±1.1) mmol/L (15 volunteers) or (5.3 ±0.6), (8.8 ±1.9), (8.5 ±2. 4), (6. 6 ± 1.4) and (4. 8 ± 1.6) mmol/L (22 volunteers) at 0, 30, 60, 120 and 180 min after oral load with seven or 7.5 ampoules of 50％ glucose injection, respectively, with no statistically significant difference between varied methods. Normal serum level of insulin was found in 38 of 60 volunteers, with their logarithmic transformation of serum insulin levels of 1.5 ± 0. 3, 3.9 ± 0. 3, 3.7 ± 0. 4, 3.2 ± 0. 6 and 2.2 ±0. 8 at 0, 30, 60, 120 and 180 min, respectively after glucose load in standard OGTT, and 20 of 38 volunteers with normal serum insulin of 1.7 ± 0. 4, 3.9 ± 0.4, 3.4 ± 0. 7, 3.3 ± 0. 8 and 2. 4 ± 0. 7 at 0,30, 60, 120 and 180 min after oral load with seven ampoules of 50％ glucose injection, respectively, or 18 of 38 with normal serum insulin of 1.7 ± 0. 4, 3.9 ± 0. 4, 3.8 ± 0. 5, 3. 3 ± 0. 7 and 2. 3 ± 1.0 at 0, 30,60, 120 and 180 min after oral load with 7. 5 ampoules of 50％ glucose injection, respectively, with no statistically significant difference between varied methods. Twenty-two cases of high serum level of insulin were found from 60 volunteers with standard OGTT, with their logarithmic transformation of serum insulin of 2.2±0.6, 4.7 ±0.5, 4.9±0.7, 4.2 t 1.0 and 2. 8 ±0.9 at0, 30, 60, 120 and 180 min after oral load with 75 g anhydrous glucose powder, respectively; 10 of 22 volunteers were found with high serum insulin level of its logarithmic transformation of 2. 4 ± 0. 6, 4. 7 ± 0. 5, 4. 7 ± 0. 3, 4. 1 ± 0. 8 and 2. 8 ± 1.1 at 0,30, 60, 120 and 180 min after oral load with seven ampoules of 50％ glucose injection, respectively ; and 12 of 22 volunteers were found with high serum insulin level of its logarithmic transformation of 1.9 ± 0. 5,4. 5 ± 0. 6, 4. 6 ± 0. 6, 3. 7 ± 1.0 and 2. 4 ± 0. 9 at 0, 30, 60, 120 and 180 min after oral load with 7. 5ampoules of 50％ glucose injection, respectively; with no significant difference between varied methods.There also was no statistically significant difference in occurrence of adverse effects between these three OGTT methods. Conclusions Either seven or 7. 5 ampoules of 50％ glucose injection can substitute 75 g anhydrous glucose powder in OGTT, with similar test results and safety.

Key words: 
Diabetes mellitus; Glucose tolerance test; Anhydrous glucose powder; 50％glucose injection