Diabetes test
and Maria Franz, M.Sc. Biochemistry and medical student Updated onDr. med. Julia Schwarz is a freelance writer in the medical department.
More about the expertsMaria Franz has been a freelance writer in the editorial team since 2020. After completing a master's degree in biochemistry, she is currently studying human medicine in Munich. With her work at she would like to arouse her own great interest in medical topics among the readers as well.
More about the experts All content is checked by medical journalists.A diabetes test is supposed to determine whether you have diabetes. For this purpose, the blood and urine are examined and, if necessary, an oral glucose tolerance test (oGTT) is carried out. A diabetes self-test for home use can only be used as a guide and should not replace a visit to the doctor. Find out how the various examinations work and what the results reveal.
ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. E11E10E13O24H36E12E14
How does the doctor diagnose diabetes mellitus?
A doctor's visit is essential for a reliable diagnosis of diabetes. The examinations can either be carried out by your family doctor or a specialist in internal medicine and endocrinology (diabetologist). A detailed preliminary talk and a general physical examination are the basis of the diagnosis. There are also several special examinations:
Measurement of fasting blood sugar
The fasting blood sugar test is particularly important for the diagnosis of diabetes. To do this, the doctor takes blood from the patient's vein and has it checked for sugar. It is important that eight hours before the morning blood sample is taken, no food and, if necessary, unsweetened and calorie-free drinks such as tea or water are consumed.
In healthy people, the fasting blood sugar is below 100 milligrams per deciliter (mg / dl). At values between 100 and 125 mg / dl there is already a disturbed sugar metabolism (prediabetes), but no manifest diabetes mellitus. If fasting blood sugar values are measured several times (on different days) above 125 mg / dl, the doctor diagnoses diabetes mellitus.
Measurement of occasional blood sugar
A blood sample for the casual blood sugar can be taken at any time of the day. If the value is repeatedly (at least 2 times) above 200 mg / dl and the patient has the typical symptoms of diabetes, diabetes mellitus is present.
Simple strip tests to determine blood sugar levels are not sufficient for diagnosing diabetes - whether on an empty stomach in the morning or at a randomly selected time of day.
Oral glucose tolerance test
The oral glucose tolerance test (oGTT) is a diabetes test with which the efficiency of the glucose metabolism can be assessed more precisely. It is not a routine examination, but is used when the diagnosis is unclear but there is a suspicion of impaired sugar metabolism.
During pregnancy, doctors usually have the test routinely carried out between the 24th and 28th week of pregnancy in order to detect gestational diabetes in good time. However, if you have already known diabetes mellitus, you do not use the test because the blood sugar levels could rise dangerously.
The oGTT works as follows: The patient should first eat a lot of carbohydrates for three days (at least 150 grams per day) and then not consume anything for 12 hours. Then blood is drawn and the fasting blood sugar is determined.
The patient then quickly drinks a sugar solution containing 75 grams of glucose. Another blood sugar test is carried out two hours later (in the case of pregnant women, this is also done after an hour).
If the blood sugar value is at or above 200 mg / dl after two hours, the diagnosis is "diabetes mellitus". Values between 140 and 200 mg / dl speak for a so-called disturbed glucose tolerance, ie a preliminary stage of diabetes (“prediabetes”) with already disturbed glucose utilization.
Diabetes urine test
A urine test is also one of the standard tests for diabetes. Normally there is little or no sugar in the urine because the kidneys hold it back when filtering the blood (absorbed). However, if the blood sugar level is significantly increased, the kidney's ability to reabsorb is no longer sufficient. So the urine contains glucose and the test field on the diabetes test strip changes color.
However, a positive diabetes urine test is not yet proof of diabetes, but merely the starting point for further investigations. This is important to know for people who use the test strip as a diabetes self-test: The sugar content in the urine can also rise in the case of other diseases, especially the kidneys, or after minor "nutritional sins" and the "diabetes test" can be positive.
If the doctor has the urine examined in a laboratory, he can also have other values determined, for example the protein content in the urine. If a diabetes that has not been discovered for a long time has already damaged the kidneys (diabetic nephropathy), this is often increased.
HbA1c value
The so-called HbA1c value is the proportion of the red blood pigment hemoglobin that has bonded with sugar molecules in the blood - the so-called glycohemoglobin A. In healthy people with permanently normal blood sugar values, the proportion of HbA1c is below 5.7 percent. However, if the blood sugar levels are increased in phases or permanently, the HbA1c level also increases. In diabetics, the HbA1c value is at least 6.5 percent.
Once established, the connection between red blood pigment and glucose remains as long as the red blood cells are alive. This is why the HbA1c value can also be used as a long-term blood sugar memory: It allows conclusions to be drawn about the blood sugar course over the past two to three months and is therefore well suited for monitoring the progress of diabetes and the success of the therapy. As a single value, it is less suitable for diagnosing diabetes.
Diabetes self-tests
Diabetes is a chronic disease with sometimes serious consequences. It is therefore recommended that healthy people also have regular tests for diabetes. This is especially true if the family has a history of diabetes. Some test procedures are also suitable for self-implementation. Although they do not allow a reliable diagnosis, a positive result should lead to a further medical examination.
Diabetes test strips
Most pharmacies run an inexpensive self-diabetes test. This is a simple variant of the urine test described in detail above. The test strip is held briefly in the urine stream when urinating. If the test field changes color, there is sugar in the urine. The doctor should then initiate further diabetes diagnostics.
There are also at home strip testers that test the blood. They are also used by diabetics who regularly inject insulin. To do this, the patient pricks his fingertip and the drop of blood that escapes is examined for its sugar content.
In the case of strip test devices, blood sugar values may by law deviate from the actual value by a maximum of 15 percent. They are therefore not a substitute for a doctor's diagnosis.
Online Diabetes Risk Test
The personal risk of developing diabetes within the next ten years can be determined using the FINDRISK online questionnaire developed by the German Diabetes Foundation and the German Diabetes Society. He asks questions about age, diabetes in the family, body weight and diet, and certain laboratory values. It cannot replace a visit to the doctor, but it allows important conclusions to be drawn early on as to how the risk of developing diabetes can be reduced.
The same applies to the German Diabetes Risk Test from the German Nutrition Institute (DIfE) for people between 35 and 65 years of age. It is based on findings from a large European study (EPIC study - European Prospective Investigation into Cancer and Nutrition). It is also not a diabetes test in the narrower sense, but it can help to identify and reduce the risk of disease at an early stage.
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