Oral glucose tolerance test
Oral glucose tolerance test ( PTTG) is required for patients with fasting blood glucose levels from 6.1 to 7 mmol / L, as well as for people with identified risk factors for developing diabetes mellitus( diabetes mellitus in close relatives, the birth of a largefetus, a violation of glucose tolerance in history, obesity, hypertension).
For the test, a patient of 3 days should receive a diet containing at least 125 g of carbohydrates( this requirement is met by all tables of hospital nutrition).The sample is taken in the morning after 10-14 hours of fasting. The initial blood sample is taken on an empty stomach, then the patient takes 75 g of glucose dissolved in 200 ml of water( children - in a dose of 1.75 g / kg, but not more than 75 g).The blood sample is recaptured after 120 minutes.
When carrying out PTGT, the following indicators are important.
■ With normal tolerance, the plasma glucose concentration after 2 hours after the load is less than 7.8 mmol / l( <140 mg%).
■ Increased plasma glucose concentration 2 hours after the load> 7.8 mmol / L( > 140 mg%), but below 11.1 mmol / L( <200 mg%) indicates impaired glucose tolerance.
■ The concentration of glucose in the blood plasma after 2 hours after a load of more than 11.1 mmol / l( & gt; 200 mg%) indicates a preliminary diagnosis of diabetes mellitus
The types of blood glucose curves for PTTG are shown in Fig.and in Fig.the algorithm for diagnosis of diabetes mellitus is presented.
To evaluate the results of PTGT, two indicators are calculated: hyperglycemic and hypoglycemic coefficients.
■ Hyperglycemic coefficient - the ratio of glucose concentration after 30 or 60 min after the load( take the highest value) to its concentration on an empty stomach. Normally this coefficient should not be above 1.7.
Fig. Types of blood glucose concentration curves for PTTG.Changes in glucose concentration in hyperinsulinism( 1), in healthy individuals( 2), in thyrotoxicosis( 3), in lung( 4), and in severe( 5) diabetes mellitus
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Fig. Types of blood glucose concentration curves for PTTG.The change in glucose concentration in hyperinsulinism( 1), in healthy individuals( 2), in thyrotoxicosis( 3), in mild( 4), and in severe( 5) diabetes mellitus
Fig. Algorithm for diagnosis of diabetes mellitus( venous blood)
Fig. Algorithm for diagnosis of diabetes mellitus( venous blood)
■ Hypoglycemic coefficient - the ratio of glucose concentration in 2 hours after the load to its concentration on an empty stomach. Normally this coefficient should be less than 1.3.
If, in accordance with the above WHO criteria, the patient does not exhibit glucose tolerance disorders, but the value of one or both of the coefficients exceeds normal values, the glucose loading curve is interpreted as "questionable".Such a patient is recommended to refrain from abusing carbohydrates and repeat the test after 1 year. The causes of impaired glucose tolerance are set out in the following table.
In evaluating the treatment of diabetic patients, it is important to evaluate the effectiveness of the treatment. WHO experts developed criteria for the compensation of diabetes mellitus, which are presented in the following table. Table 1. Causes of impaired glucose tolerance
Table Compensation criteria for diabetes mellitus
Table Compensation criteria for diabetes mellitus
Type 1 diabetes mellitus
Type 1 diabetes mellitus
Diabetes mellitus type 2