Missed diagnosis of diabetes often occurs, especially when ordinary physical examinations only measure fasting blood sugar, so prediabetes cannot be found. This article summarizes five common reasons for misdiagnosis of diabetes to help everyone get rid of misunderstandings in diagnosing diabetes.
1. If the patient has the typical symptoms of "three more and one less" (polydipsia, polyphagia, polyuria and weight loss), as long as the fasting blood sugar is ≥7.0mmol/L, or the 2-hour postprandial blood sugar is ≥11.1mmol/L, or the patient takes 75 Diabetes can be diagnosed if the 2-hour blood sugar of glucose powder is ≥11.1mmol/L, or the random blood sugar is ≥11.1mmol/L.
2. If the patient does not have the typical symptoms of "three more and one less", he or she needs to test his blood sugar again on another day. If the results of both blood sugar tests meet the above standards, he can also be diagnosed with diabetes.
In addition, when diagnosing diabetes, attention should be paid to excluding transient increases in blood sugar caused by stress factors such as acute infection, high fever, severe trauma, etc.
According to the above criteria, clinical diagnosis of diabetes is not difficult. But in fact, it is not uncommon for diabetes to be missed or misdiagnosed in grassroots community hospitals.
Teacher Wang Jianhua summarized the causes of misdiagnosis into the following five aspects and analyzed them one by one, aiming to improve the clinical diagnosis level of grassroots doctors and reduce the misdiagnosis rate of diabetes.
Mistake 1: Diagnosing diabetes based solely on the symptoms of “three more and one less”
Some patients and even a few grassroots doctors mistakenly believe that all diabetic patients have the symptoms of "three more and one less" (i.e. "poor drinking, polyuria, polyuria and weight loss"). If the patient does not have the "three more and one less" symptoms, , diabetes can be ruled out.
As a result, many diabetic patients with mild or no symptoms are easily missed, which is very common in the elderly population.
Analysis: Under normal circumstances, only when blood sugar rises significantly (more than 10mmol/L), patients will have symptoms of "three more and one less".
According to the above diagnostic criteria for diabetes, diabetes can be diagnosed as long as fasting blood sugar ≥7.0mmol/L. It can be seen that for those diabetic patients with fasting blood sugar between 7.0mmol/L and 10.0mmol/L, if they simply rely on "three more and one" If the diagnosis is based on "few" symptoms, the diagnosis will most likely be missed.
It should be pointed out that "thirst, polydipsia, and polyuria" are not unique to diabetes. Certain other endocrine diseases (such as diabetes insipidus) can also present the above symptoms. Therefore, we cannot diagnose or rule out diabetes based solely on symptoms.
To sum up, symptoms are not a necessary condition for diagnosing diabetes. The key is to see whether blood sugar reaches the standard. The latter is the gold standard for diagnosing diabetes. As long as two blood glucose test results meet the diagnostic criteria, the patient can be diagnosed with diabetes even if he has no symptoms.
Mistake 2: Diagnosing diabetes based on urine glucose results
In the eyes of many people, diabetic patients must have sugar in their urine, otherwise it is not diabetes. This view is actually wrong.
Analysis: When the blood sugar level is normal, all the glucose filtered out when the blood flows through the glomerulus can be reabsorbed into the blood by the renal tubules, so the urine glucose test is negative.
When blood sugar rises to a certain level, the glucose in the glomerular filtrate cannot be completely reabsorbed by the renal tubules, and the remaining part is excreted in the urine, so the urine glucose test is positive. When kidney function is normal, blood sugar and urine sugar are consistent, that is, the higher the blood sugar, the higher the urine sugar.
Medically, the lowest blood sugar level at which urine glucose occurs is called the "renal glucose threshold." The renal glucose threshold of normal adults is about 10mmol/L, and the renal glucose threshold of the elderly is even higher than this. In other words, urine glucose will be positive only if the blood sugar concentration of diabetic patients is at least 10mmol/L. We know that diabetes can be diagnosed as long as fasting blood glucose ≥7.0mmol/L.
For those early-stage mild diabetic patients with fasting blood sugar between 7.0 and 10mmol/L, if the diagnosis is based on positive urine glucose, these patients will be missed.
Furthermore, positive urine sugar does not necessarily mean diabetes. For example, in some renal tubular diseases, due to the impairment of glucose reabsorption by the renal tubules, although the patient's blood sugar is normal, the urine sugar is positive. We call this "renal glycosuria" ; Also, during pregnancy, women's renal glucose threshold often decreases, and they may also have normal blood sugar and positive urine sugar.
Therefore, diabetes cannot be diagnosed or excluded based on whether urine glucose is positive or not. Instead, the diagnosis of diabetes should be based on fasting, two-hour postprandial blood glucose or glucose tolerance test results.
Mistake 3: Only check fasting blood sugar, not postprandial blood sugar
When it comes to blood sugar testing, people are often accustomed to taking fasting blood tests and think that as long as fasting blood sugar is normal, there is no diabetes. This is not necessarily the case. According to domestic and foreign epidemiological surveys, only checking fasting blood glucose will lead to at least 60% of diabetic patients being missed.
Analysis: In the early stages of type 2 diabetes, although patients' pancreatic beta cells are damaged, they still retain part of the function of secreting insulin. Therefore, patients often have normal fasting blood sugar and elevated postprandial blood sugar. When blood sugar rises after a meal and exceeds 11.1mmol/L, diabetes can also be diagnosed.
Therefore, when diagnosing diabetes, you should not only check fasting blood sugar, but also pay attention to blood sugar testing 2 hours after a meal. For obese people with fasting blood glucose greater than 5.6mmol/L, a glucose tolerance test (OGTT) should be performed routinely to avoid missed diagnosis.
Mistake 4: Using blood glucose meter results to diagnose diabetes
Nowadays, many community clinics and diabetic patients have blood glucose meters. It has the advantages of convenience and speed, and is very suitable for out-of-hospital blood glucose monitoring. However, some people use the test results of the blood glucose meter to diagnose diabetes, which is inappropriate because there are certain differences between the test results of the blood glucose meter and the test results of the hospital's biochemical analyzer.
Analysis: According to WHO regulations, the diagnosis of diabetes is based on the blood glucose measurement results of venous plasma (note: the remaining part after blood separation removes red blood cells and other formed components is plasma), and the blood glucose meter measures capillary whole blood glucose. It is 10% to 15% lower than venous plasma blood sugar.
Therefore, if the test results of a rapid blood glucose meter are used to diagnose diabetes, it is easy to miss early diabetic patients with mildly elevated fasting blood sugar. The blood glucose meter can only be used to monitor the condition of diabetes and cannot be used as a basis for diagnosing diabetes. To diagnose diabetes, you must go to the hospital to draw venous blood and test it with a large biochemical instrument.
Mistake 5: Failure to rule out the influence of stress factors
Is it possible to test blood sugar casually, and as long as the diagnostic criteria are met, diabetes can be diagnosed? The answer is: "No".
Analysis: We know that stress factors such as infection, high fever, trauma, and surgery can cause a transient increase in blood sugar. As the stress factors are relieved, blood sugar can return to normal. Therefore, the diagnosis of diabetes needs to exclude stress factors. In other words, the blood glucose test results after the stress state is eliminated should be used as the basis for determining diabetes.
Finally, it should be noted that the diagnosis of diabetes based on blood sugar levels is only a "qualitative diagnosis", and then a "type diagnosis" of diabetes must be carried out. Diabetes is roughly divided into four major types: type 1 diabetes, type 2 diabetes, gestational diabetes, and other special types of diabetes (formerly known as "secondary diabetes").
Diabetes caused by certain drugs (such as glucocorticoids, diuretics), chronic liver disease, and certain endocrine diseases (such as hypercortisolism, growth hormone tumors, hyperthyroidism, etc.) are all secondary diabetes.
If you are worried that you have diabetes, you can go to the hospital for a blood test. The results of the blood glucose meter alone may not be accurate enough.
