How diabetes is diagnosed?The diagnosis of diabetes mellitus is made with the help of various blood tests. During this process, the sugar concentration in the blood is determined at different points in time. The doctor then compares the results with the standard values.
– The symptoms of diabetes usually appear gradually. – Blood glucose concentrations between 100 and 125 mg/dl (5.6 to 6.9 mmol/l) are referred to as prediabetes. – If the blood sugar level is 200 mg/dl (11.1 mmol/l), diabetes is suspected. – If the value exceeds 126 mg/dl (7.0 mmol/l) in a fasting blood glucose test, the doctor usually makes a diabetes diagnosis. – An oral glucose tolerance test is used to determine whether the disease is diabetes mellitus or gestational diabetes. – The HbA1c value is the long-term blood glucose value, which is more than 6.5 percent when diabetes is diagnosed.
What is diabetes mellitus?
Diabetes mellitus is a metabolic disease. The body no longer produces enough insulin, so sugar is less able to pass from the blood into the cells. While type 1 diabetes is congenital, type 2 diabetes only develops over time. Type 2 diabetes is usually preceded by prediabetes.
Do I have diabetes? Which symptoms indicate diabetes mellitus
Diabetes does not become apparent through sudden, clear symptoms. Elevated blood glucose levels are only detectable during routine check-ups with the primary care physician. Usually not noticed by the patient at first. While there are some symptoms that can indicate type 2 diabetes and lead to a diagnosis of diabetes. However, they often appear at a very late stage in the course of the disease.
Symptoms include an increased feeling of thirst, frequent urination, weight loss or weight gain, fatigue, mental health problems, failing eyesight, or poorly healing wounds.
Diagnosis of diabetes: what tests are available?
There are different tests for diagnosing diabetes, which follow different diabetes diagnostic criteria depending on the patient's individual clinical picture:
Occasional blood test
If the affected person does not notice any of the typical diabetes symptoms, elevated blood glucose levels are often only noticed in the course of an occasional blood test. Usually, a physician performs such a blood test in combination with other examinations as a purely routine test; the patient may have already eaten something beforehand.
If the blood glucose level is over 200 mg/dl (11.1 mmol/l) on an occasional test, diabetes is suspected. The doctor then performs a blood glucose test on an empty stomach to confirm the diabetes diagnosis.
Fasting blood glucose test
The fasting blood glucose test is performed when there is a definite suspicion of diabetes due to existing symptoms or when blood glucose levels are already elevated. It is important for this test that the patient has not eaten any food for at least eight hours before the blood sample is taken.
If the blood glucose value is above 126 mg/dl (7.0 mmol/l), the diagnosis of diabetes mellitus is confirmed. This test is repeated on another day to confirm the diagnosis of diabetes mellitus. A blood glucose value between 100 and 125 mg/dl (5.6 to 6.9 mmol/l) usually indicates prediabetes. In contrast to the diagnosis of diabetes mellitus, affected individuals can counteract prediabetes by changing their lifestyle. In this way, the onset of type 2 diabetes can often be delayed and, in the best case, even prevented.
Oral glucose tolerance test (OGTT)
The oral glucose tolerance test is performed when the diagnosis of diabetes is not yet clear or to determine if it is gestational diabetes or "normal" diabetes mellitus.
This blood test is also performed on an empty stomach. Prior eating and drinking is not allowed; only drinking water is possible. After the first blood sample is taken, the patient drinks a liquid containing concentrated glucose. After two hours, another blood sample is taken.
If blood glucose levels drop rapidly into the normal range, a diabetes diagnosis is usually ruled out. If the value is above 200 mg/dl (11.1 mmol/l) after two hours, it is very likely to be diabetes mellitus. A value between 140 and 199 mg/dl (7.8 and 11 mmol/l) indicates prediabetes.
The HbA1c value is the so-called blood glucose memory. This value shows the average amount of sugar attached to hemoglobin, the pigment in red blood cells. On the basis of this value the doctor determines the height of the blood sugar of the last six to eight weeks.
The diagnosis of diabetes exists if the HbA1c value is above 6.5 percent (48 mmol/mol). For comparison: healthy people have a value of 5 percent (about 30 mmol/mol). Since 2010, this value has been expressed internationally in millimoles per mole (mmol/mol) and no longer in percentages. The test of the HbA1c-value serves in the course of the illness also for the control of the correct blood sugar adjustment with patients with diabetes mellitus.