Oral glucose tolerance test

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Classification according to ICD-10
R73.0 Impaired glucose tolerance
ICD-10 online (WHO version 2019)

The oral glucose tolerance test (abbreviated oGTT ), also known as the sugar load test , is used to detect a disturbed glucose metabolism (glucose tolerance disorder) and thus in particular to diagnose diabetes mellitus . The patient drinks a precisely defined amount of glucose that is dissolved in water. In principle, it is also possible to deliver the sugar by intravenous injection, but this form is rarely used in human medicine in everyday clinical practice, but in examinations of animals.

Oral glucose exposure is also used in a modified form to diagnose other endocrinological disorders ( STH suppression test for acromegaly , extended oGTT for up to 6 hours if hypoglycaemia is suspected, e.g. in the case of an insulinoma ). The examination is contraindicated in the presence of manifest diabetes mellitus .

Test principle

The idea is to determine the body's ability to regulate blood glucose with the help of strong stimulation from ingested sugar. Glucose dissolved in water is used for this, as it is the form of sugar that the body can absorb the fastest and leads to a steep increase in blood glucose concentration (corresponds to the determination of a system response in systems theory ). This increase in blood sugar stimulates and regulates the pancreas with the secretion of insulin , which stimulates blood sugar-lowering reactions in the liver , muscles and fat cells. During the oGTT, the blood sugar value, possibly also the insulin value, is measured periodically over time: fasting value, increase, maximum value and decrease in blood sugar up to the fasting value.

With an oGTT, the body's ability to regulate both strength and speed can be determined, which allows diagnostic statements to be made with appropriate reference values. For example, if there is a delay in the drop in fasting sugar levels, it can be concluded that there is insulin resistance or a reduced ability to secrete insulin; if the maximum glucose level is too high or if fasting glucose levels are not reached within a defined period of time, pronounced diabetes mellitus .

Indication as a diagnostic method

The WHO generally recommends the oGTT as a diagnostic tool, even against concerns about effort and costs. This is justified with the poor sensitivity of a pure fasting sugar level determination; According to the cited DECODE study, around 30% of diabetics are not detected as a result. A disturbed glucose tolerance (IGT) can only be discovered through an oGTT.

In the 2007 guideline, the German Diabetes Society (DDG) suggests shorter-interval screening with an oGTT if the following risk factors are present:

It should also be noted that the HbA 1c - or fructosamine value are unsuitable for a diabetes screening. In a statement from 2010, the DDG followed the American Diabetes Association (ADA) and recognized HbA1c as a suitable parameter for diagnosing diabetes (HbA1c: 6.5%) or for people with an increased risk of diabetes (HbA1c: 5.7 to 6 , 4%).

Contraindications

Contraindications for the oGTT are acute illnesses , according to the DDG intercurrent illnesses (e.g. after gastrointestinal resections or gastrointestinal illnesses with changed absorption) or an already manifested diabetes mellitus .

Recommended procedure by the German Diabetes Society

According to the German Diabetes Society (DDG), the test should be carried out in the morning on the patient who has previously fasted for ten hours. In order to obtain a meaningful result, the patient must have fed on at least 150 g of carbohydrates per day for the three preceding days or as before (diet attempts, for example to obtain a more favorable result, can distort the measurement). In addition, there must be no febrile illness and there must be a three-day interval before and after menstruation . During the test, the patient must not eat, drink, smoke or be physically active.

Commercially available measuring devices for blood sugar self-monitoring are not approved for diagnostics due to the permissible fluctuation range of the measurement results (up to 15%).

procedure
  • 0 min: blood sample for fasting glucose determination (venous plasma)
  • Then take a defined amount of glucose (75 g, for children 1.5 g per kg body weight), which was dissolved in 250-300 ml of water. The liquid must be drunk within 5 minutes.
  • multiple blood sampling for glucose determination (venous plasma) after 60 min (only to determine gestational diabetes) and 120 min, with an extended test after 60 minutes or e.g. B. Occurrence of hypoglycaemia.

OGTT and gestational diabetes

ADA Criteria for Screening Gestational Diabetes
(Carpenter and O'Sullivan's Criteria)
Time of measurement
(100-g glucose 3-h oGTT) 		Normal values
(test negative if 3 fulfilled)
sober <95 mg / dl
<5.3 mmol / l
after 1 hour <180 mg / dl
<10.0 mmol / l
after 2 hours <155 mg / dl
<8.6 mmol / l
after 3 hours <140 mg / dl
<7.8 mmol / l

To determine gestational diabetes, the test can be carried out between the 24th and 28th week of pregnancy as part of preventive care. In Germany, this test has been part of the maternity guidelines since March 2012 and is therefore a service of the statutory health insurance companies.

Currently (as of March 2013) the following health insurance companies offer the test for their insured persons:

The offers of the health insurance companies change frequently. In some cases, there are also country-specific contracts between the statutory health insurance associations and the health insurance companies.

The American Diabetes Association (ADA) recommends a 3-hour oGTT (with 100 g glucose) for screening for gestational diabetes, if a 1-hour oGTT (with 50 g glucose) with a blood sugar value ≥ 140 mg / dl (≥ 7, 8 mmol / l) is noticeable. Carpenter's and O'Sullivan's criteria are highly sensitive for a wide range of women (age, ethnicity, etc.) and are therefore considered reliable indicators.

interpretation

Classifications according to the diabetes guidelines of the DDG, as of 2019  
classification Fasting blood sugar (venous) Blood sugar in the oGTT
after 2 hours (venous)
no diabetes <100 mg / dl
<5.6 mmol / l		 <140 mg / dl
<7.8 mmol / l
Abnormal
Fasting Glucose (IFG)		 100-125 mg / dl
5.6-6.9 mmol / l		 k. A.
Impaired
glucose tolerance (IGT)		 <126 mg / dl
<7.0 mmol / l		 140-199 mg / dl
7.8-11.0 mmol / l
Diabetes mellitus ≥ 126 mg / dl
≥ 7.0 mmol / l		 ≥ 200 mg / dl
≥ 11.1 mmol / l
Diabetes diagnostic criteria and WHO classifications as of 2006  
classification Fasting blood sugar (venous) Blood sugar in the oGTT
after 2 hours (venous)
normal <110 mg / dl
<6.1 mmol / l		 <140 mg / dl
<7.8 mmol / l
Abnormal
Fasting Glucose (IFG)		 110-125 mg / dl
6.1-6.9 mmol / l		 <140 mg / dl
<7.8 mmol / l
Impaired
glucose tolerance (IGT)		 <126 mg / dl
<7.0 mmol / l		 140-199 mg / dl
7.8-11.0 mmol / l
Diabetes mellitus ≥ 126 mg / dl
≥ 7.0 mmol / l		 ≥ 200 mg / dl
≥ 11.1 mmol / l

Possible disruptive factors

An oGTT can be false positive for:

To false negative results may result in:

  • Malabsorption
  • Taking medication (lowering blood sugar)
  • physical activity, smoking during the trial period
  • u. v. a.

For the 75 g oGTT, which lasts 2 hours, the test persons should eat at least 150 g to a maximum of 250 g carbohydrates daily for standardization 3 days beforehand. The test is carried out after 10-14 hours of food abstinence.

literature

  • Richard Daikeler, Götz Use, Sylke Waibel: Diabetes. Evidence-based diagnosis and therapy. 10th edition. Kitteltaschenbuch, Sinsheim 2015, ISBN 978-3-00-050903-2 , p. 22 f.

Individual evidence

  1. ↑ What diagnostic tests should be used to define glycaemic status? ( English , pdf; 1.6 MB) In: Definition and Diagnosis of Diabetes Mellitus and Intermediate Hyperglycemia . www.who.int. S. 30. 2006. Retrieved February 20, 2011.
  2. ↑ DECODE Study Group .: Will new diagnostic criteria for diabetes mellitus change phenotype of patients with diabetes? Reanalysis of European epidemiological data . In: The Lancet . 21; 354 ​​(9179), Oct 21, 1999, pp. 610-611. doi : 10.1016 / S0140-6736 (98) 12131-1 . PMID 10466661 . Retrieved February 20, 2011.
  3. ^ W. Kerner: Definition, classification and diagnosis of diabetes mellitus (pdf) In: Diabetologie 2007 . German Diabetes Society. Pp. 147-149. October 12, 2007. Archived from the original on December 16, 2007. Retrieved on February 20, 2011.
  4. ^ Definition, classification and diagnosis of diabetes mellitus. ( Memento from February 28, 2013 in the Internet Archive ) (PDF; 1.1 MB).
  5. ↑ a b Assiamira Ferrara et al .: Prevalence of Gestational Diabetes Mellitus Detected by the National Diabetes Data Group or the Carpenter and Coustan plasma glucose thresholds . In: care.diabetesjournals.org (Ed.): Diabetes Care . 25, No. 9, September 1, 2002, pp. 1625-1630. doi : 10.2337 / diacare.25.9.1625 . Retrieved February 21, 2011.
  6. ↑ Guidelines on medical care during pregnancy and after delivery (maternity guidelines): Introduction of screening for gestational diabetes. G-BA, December 15, 2011 (PDF; 255 kB).
  7. ↑ Diabetes in pregnancy . aokplus-online.de. Retrieved March 12, 2013.
  8. ↑ Gestational diabetes test . barmer-gek.de. Archived from the original on December 19, 2015. Retrieved March 12, 2013.
  9. ↑ Gestational diabetes screening: additional service for more safety during pregnancy . bkk-mobil-oil.de. Archived from the original on November 17, 2011. Retrieved July 12, 2011.
  10. ↑ Gestational diabetes . hkk.de. Retrieved March 12, 2013.
  11. ↑ Safely into family happiness | TK current. In: tk-aktuell.tk.de. Archived from the original on May 2, 2016 ; accessed on May 2, 2016 .
  12. ↑ A. Petersmann: Definition, classification and diagnosis of diabetes mellitus (pdf; 2.2 MB) In: Diabetologie 2019 . German Diabetes Society. Pp. S111-S118. October 2019. Retrieved November 26, 2019.
  13. ↑ Definition and Diagnosis of Diabetes Mellitus and Intermediate Hyperglycemia ( English , pdf; 1.6 MB) In: World Health Organization . www.who.int. P. 36. 2006. Retrieved February 20, 2011.
  14. ^ Katharina Müller, Sönke Müller: Original examination questions with commentary GK 2, Clinical Chemistry . 15th edition. Thieme, Stuttgart 2002, ISBN 3-13-112595-0 , p. 47 ( limited preview in Google Book search).
  15. ^ A b Andreas Schäffler, L. Cornelius Bollheimer, Roland Büttner, Christiane Girlich, C. Aslanidis, W. Dietmaier, M. Bala, V. Guralnik, T. Karrasch and S. Wurm: Carbohydrate metabolism . In: Andreas Schäffler (Ed.): Functional diagnostics in endocrinology, diabetology and metabolism: indication, test preparation, test execution, interpretation . 2nd Edition. Springer, Berlin 2013, ISBN 978-3-642-29689-5 , pp. 9 ff ., doi : 10.1007 / 978-3-642-29690-1 ( limited preview in the Google book search).
This text is based in whole or in part on the entry Oral Glucose Tolerance Test in Flexikon , a wiki from DocCheck . The takeover took place on July 8, 2004 under the then valid GNU license for free documentation .