Editing Glucose tolerance test (section)

===Preparation===
The patient is instructed not to restrict [[carbohydrate]] intake in the days or weeks before the test.<ref>{{cite journal|doi=10.1210/jendso/bvab049|title=Carbohydrate Intake Prior to Oral Glucose Tolerance Testing |year=2021 |last1=Klein |first1=Klara R. |last2=Walker |first2=Christopher P. |last3=McFerren |first3=Amber L. |last4=Huffman |first4=Halie |last5=Frohlich |first5=Flavio |last6=Buse |first6=John B. |journal=Journal of the Endocrine Society |volume=5 |issue=5 |pages=bvab049 |pmid=33928207 |pmc=8059359 |doi-access=free }}</ref> The test should not be done during an illness, as results may not reflect the patient's glucose metabolism when healthy. A full adult dose should not be given to a person weighing less than 42.6&nbsp;kg (94&nbsp;lb), or the excessive glucose may produce a [[false positive]] result. Usually the OGTT is performed in the morning as glucose tolerance can exhibit a diurnal rhythm with a significant decrease in the afternoon. The patient is instructed to [[fasting|fast]] (water is allowed) for 8–12 hours prior to the tests. Medication such as large doses of [[salicylates]], [[diuretics]], [[anticonvulsants]], and [[oral contraceptives]] affect the glucose tolerance test.<ref>{{Cite journal |last1=Salvaggio |first1=Heather L |last2=Zaenglein |first2=Andrea L |date=2010-08-09 |title=Examining the use of oral contraceptives in the management of acne |journal=International Journal of Women's Health |volume=2 |pages=69–76 |doi=10.2147/ijwh.s5915 |issn=1179-1411 |pmc=2971728 |pmid=21072299 |doi-access=free }}</ref>