Editing Glucose tolerance test (section)

==Variations==
A standard two-hour GTT (glucose tolerance test) is sufficient to diagnose or exclude all forms of diabetes mellitus at all but the earliest stages of development.

Longer tests have been used for a variety of other purposes, such as detecting reactive hypoglycemia or defining subsets of [[hypothalamic obesity]]. Insulin levels are sometimes measured to detect insulin resistance or deficiency.<ref>{{Cite journal |last1=Lv |first1=Xue |last2=Fang |first2=Kun |last3=Hao |first3=Wenqing |last4=Han |first4=Yuxin |last5=Yang |first5=Nailong |last6=Yu |first6=Qing |date=2020-12-02 |title=Identification of Reactive Hypoglycemia with Different Basic BMI and Its Causes by Prolonged Oral Glucose Tolerance Test |journal=Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy |volume=13 |pages=4717–4726 |doi=10.2147/DMSO.S280084 |issn=1178-7007 |pmc=7719337 |pmid=33293845 |doi-access=free }}</ref>

The GTT (glucose tolerance test) is of limited value in the diagnosis of reactive hypoglycemia, since normal levels do not preclude the diagnosis, abnormal levels do not prove that the patient's other symptoms are related to a demonstrated atypical OGTT, and many people without symptoms of reactive hypoglycemia may have the late low glucose.<ref>{{Cite journal |last1=Pant |first1=Vivek |last2=Mathema |first2=Safala |last3=Jha |first3=Sandeep |last4=Paudel |first4=Sujay Dutta |last5=Baral |first5=Suman |date=2021-12-07 |title=The Detection of Postprandial Hypoglycemia with 5-Hour Oral Glucose Tolerance Test |journal=EJIFCC |volume=32 |issue=4 |pages=451–457 |issn=1650-3414 |pmc=8751404 |pmid=35046763}}</ref>