Glucose tolerance test – wikipedia cure type 1 diabetes naturally

The test was based on the previous work in 1913 by A. T. B. Jacobson in determining that carbohydrate ingestion results in blood glucose fluctuations, [5] and the premise (named the Staub-Traugott Phenomenon after its first observers H. Staub in 1921 and K. Traugott in 1922) that a normal patient fed glucose will rapidly return to normal levels of blood glucose after an initial spike, and will see improved reaction to subsequent glucose feedings. [6] [7] Testing [ edit ]

The patient is instructed not to restrict carbohydrate intake in the days or weeks before the test. [ citation needed] 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 kg (94 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 fast (water is allowed) for 8–12 hours prior to the tests. Medication such as large doses of Salicylates, Diuretics, Anti-Convulsants, and oral contraceptives affect the glucose tolerance test Procedure [ edit ]

• Blood is drawn at intervals for measurement of glucose ( blood sugar), and sometimes insulin levels. The intervals and number of samples vary according to the purpose of the test. For simple diabetes screening, the most important sample is the 2 hour sample and the 0 and 2 hour samples may be the only ones collected. A laboratory may continue to collect blood for up to 6 hours depending on the protocol requested by the physician.

• In Portugal, the standard glucose load is provided by the clinical laboratory or hospital by 200 ml of fluid in a PET bottle. The best-known brand is TopStar, produced in Portugal. The recommendation is for a 75g oral dose for all adults, which is adjusted for weight in children. However, doses of 50g and 100g are also used, available in orange, lemon and cola flavor.

• Fasting plasma glucose (measured before the OGTT begins) should be below 6.1 mmol/L (110 mg/dL). Fasting levels between 6.1 and 7.0 mmol/L (110 and 125 mg/dL) are borderline ( impaired fasting glycaemia), and fasting levels repeatedly at or above 7.0 mmol/L (126 mg/dL) are diagnostic of diabetes.

• For a 2 hour GTT (Glucose Tolerance Test) with 75g intake, a glucose level below 7.8 mmol/L (140 mg/dL) is normal, whereas higher glucose levels indicate hyperglycemia. Blood plasma glucose between 7.8 mmol/L (140 mg/dL) and 11.1 mmol/L (200 mg/dL) indicate impaired glucose tolerance, and levels above 11.1 mmol/L ( 200 mg/dL) at 2 hours confirm a diagnosis of diabetes. [9]

For gestational diabetes, the American College of Obstetricians and Gynecologists (ACOG) recommends a two-step procedure, wherein the first step is a 50g glucose dose. [10] If it results in a blood glucose level of more than 7.8 mmol/L (140 mg/dL), [9] it is followed by a 100 gram glucose dose. [10] The diagnosis of gestational diabetes is then defined by a blood glucose level exceeding the cutoff value on at least two intervals, [10] with cutoffs as follows: [9]

The diagnosis criteria stated above by the World Health Organisation (WHO) are for venous samples only (a blood sample taken from a vein in the arm). An increasingly popular method for measuring blood glucose is to sample capillary or finger-prick blood, which is less invasive, more convenient for the patient and requires minimal training to conduct. Though fasting blood glucose levels have been shown to be similar in both capillary and venous samples, postprandial blood glucose levels (those measured after a meal) can vary. The diagnosis criteria issued by the WHO are only suitable for venous blood samples. Given the increasing popularity of capillary testing, the WHO has recommended that a conversion factor between the two sample types be calculated, but as of 2017 [update] no conversion factor had been issued by the World Health Organisation, despite some medical professionals adopting their own. Variations [ edit ]

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.

The GTT (Glucose Tolerance Test) is of limited value in the diagnosis of reactive hypoglycemia, since (1) normal levels do not preclude the diagnosis, (2) abnormal levels do not prove that the patient’s other symptoms are related to a demonstrated atypical OGTT, and (3) many people without symptoms of reactive hypoglycemia may have the late low glucose. Oral glucose challenge test [ edit ]

The oral glucose challenge test (OGCT) is a short version of the OGTT, used to check pregnant women for signs of gestational diabetes. [3] [13] It can be done at any time of day, not on an empty stomach. [3] The test involves 50g of glucose, with a reading after one hour. [3] Limitations of OGTT [ edit ]

The OGTT does not distinguish between insulin resistance in peripheral tissues and reduced capacity of the pancreas beta-cells to produce insulin. The OGTT is less accurate than the hyperinsulinemic-euglycemic clamp technique (the gold standard for measuring insulin resistance), or the insulin tolerance test, but is technically less difficult. Neither of the two technically demanding tests can be easily applied in a clinical setting or used in epidemiological studies. HOMA-IR ( homeostatic model assessment) is a convenient way of measuring insulin resistance in normal subjects, which can be used in epidemiological studies, but can give erroneous results for diabetic patients. [14] [15] References [ edit ]