With economic development and social progress, people’s standard of living has generally improved, lifestyles have changed dramatically, and there has been a significant increase in the incidence of obesity and diabetes. However, many people are not aware of diabetes and do not know if they have the disease even when their blood glucose is checked.
Below, we’ll learn how to diagnose diabetes.
People with diabetes
First, there are several groups of people who need to beware if they have diabetes, including:
- Have three symptoms of polyuria, thirst, drinking, eating and weight loss.
- People who have been seen for various acute and chronic complications or co-morbidities of diabetes.
- People at high risk for diabetes, including: a history of mildly elevated blood glucose; age ≥ 45 years; people who are overweight or obese; first-degree relatives (parents and siblings) with type 2 diabetes; women with a history of delivering a large baby or a history of gestational diabetes; women with polycystic ovary syndrome; and people taking long-term antidepressants.
In summary, people with these factors need to have their blood glucose checked regularly and be aware of the onset of diabetes.
Tests to diagnose diabetes
Second, diabetes should be diagnosed based on venous plasma glucose, not capillary blood glucose test results measured with a glucometer.
Oral glucose tolerance test (OGTT)
The oral glucose tolerance test (OGTT) is a test that is often used in the diagnosis of diabetes.
An oral glucose tolerance test is done when blood glucose is above the normal range but does not meet the criteria to confirm a diagnosis of diabetes. The procedure is to take 75 grams of anhydrous glucose orally, usually dissolved in 250 to 300 mL of water, in the early morning on an empty stomach after 8 hours of not eating any food, and to drink it within 5 to 10 minutes, and to measure venous blood glucose levels on an empty stomach and 2 hours after drinking the glucose water.
There are a few things to keep in mind when performing the OGTT:
- OGTT should not be performed during acute illness or stressful conditions.
- Subjects should not drink tea or coffee, smoke, or do strenuous exercise during the trial.
- Eat normally (not too little) 3 days before the trial and stop taking medications that may affect blood glucose.
Glycosylated hemoglobin (HbA1c)
Glycated hemoglobin (HbA1c) is a measure that represents a patient’s average blood glucose over the last 8 to 12 weeks. The World Health Organization and the American Diabetes Association have established HbA1c ≥ 6.5% as a diagnostic criterion for diabetes.
It is not currently used as a diagnostic criterion for diabetes because of the lack of information and the lack of standardization of testing methods in China.
Diabetes diagnostic criteria
Currently, the diagnostic criteria for diabetes are the 1999 World Health Organization criteria for diabetes and prediabetes, as shown in Tables 1 and 2:
Table 1. Diabetes Diagnostic Criteria
| Venous plasma glucose level (mmol/L) | |
|
1. diabetes symptoms* plus random blood glucose or |
≥11.1 |
|
2. Fasting blood glucose (FPG)** or |
≥7.0 |
| 3. OGTT 2-hour blood glucose | ≥11.1 |
Table 2. Classification of blood glucose status
|
normal |
Pre-diabetes | Diabetes | |
| Fasting blood glucose (mmol/L) | 3.9 to 6.0 | 6.1~6.9 | ≥7.0 |
| OGTT 2-hour blood glucose (mmol/L) | ＜7.7 | 7.8~11.0 | ≥11.1 |
* Diabetes symptoms refer to polyuria, thirst and weight loss.
** Fasting means not having eaten anything for 8 hours; any time means any time of day, regardless of the time and amount of the last meal eaten.
Prediabetes includes both impaired fasting and abnormal glucose tolerance states and should be determined by the average of two OGTT results over a 3-month period.
For people without symptoms of diabetes, when just one blood glucose value meets the diagnostic criteria for diabetes, the blood glucose must be retested on another day to clarify whether they have diabetes; if the results do not meet the diagnostic criteria for diabetes, they should be retested regularly.
It is possible to have stress hyperglycemia during a serious illness or stressful condition, and the diagnosis of diabetes cannot be made on the basis of this blood glucose; it is important to review the blood glucose after the stress has resolved to determine if you have diabetes.
Diagnosis of gestational diabetes
For pregnant women with high-risk factors (i.e., history of gestational diabetes, obesity, positive urine glucose, or family history of diabetes), the first prenatal visit during pregnancy should screen for preconception undiagnosed type 2 diabetes using the general diabetes diagnostic criteria. If the diagnostic criteria for diabetes are met, the diagnosis of diabetes prior to pregnancy is confirmed.
If the initial test result is normal, a 75-g OGTT may be performed at 24 to 28 weeks of pregnancy to screen for the presence of gestational diabetes. The diagnostic criteria for gestational diabetes are at or above at least one of the following: fasting glucose ≥ 5.1 mmol/L, 1-hour glucose ≥ 10.0 mmol/L and/or 2-hour glucose ≥ 8.5 mmol/L.