To diagnose type 2 diabetes, you need to know if you have the typical “three more, one less” symptoms, as well as fasting blood glucose, 2-hour postprandial blood glucose, random blood glucose, and glycated hemoglobin levels.
Take a medical history
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At the first exam, the doctor will ask for a detailed history and whether there are any symptoms associated with the condition. In addition to the typical “three more, one less” symptoms, some patients may already have complications of diabetes, such as loss of vision and numbness in the lower extremities, which the doctor will initially determine.
Fast blood glucose
Outpatients can come to the hospital early for blood testing, fasting 8 to 10 hours in advance and not being overly stressed during the blood draw to avoid a poor draw. Type 2 diabetes is diagnosed if fasting blood glucose is ≥7.0 mmol/L.
2-hour postprandial blood glucose
Patients fast for 8 to 10 hours without eating anything, drink a small amount of water, and have fasting blood tests for fasting glucose and fasting insulin levels early in the morning, followed by 75 grams of anhydrous glucose dissolved in 300 mL of water and drunk within 5 minutes, starting with the first sip and measuring glucose and insulin 2 hours after taking the glucose, without tea and coffee, smoking, or strenuous exercise during this period.
The diagnosis of type 2 diabetes is confirmed if the blood glucose level is ≥11.1 mmol/L 2 hours after the oral glucose load and if there are the typical symptoms of “three more and one less”. Some patients may be less symptomatic and need to be rechecked again. If the 2-hour glucose level is still ≥11.1 mmol/L after oral glucose loading, the diagnosis of type 2 diabetes is confirmed.
Random blood glucose
A blood test taken at any time of the day, regardless of fasting or eating, with a blood glucose level of ≥11.1 mmol/L and the classic symptoms of “three more, one less,” confirms the diagnosis of type 2 diabetes.
The results of these tests are available the same day, and the cost of the tests is not high, about a few dollars. For some patients, the symptoms are not obvious and it is difficult to determine whether the patient has type 2 or type 1 diabetes, so the doctor may add a C-peptide test or an autoantibody test to confirm the diagnosis.
Other tests
Some patients have complications of type 2 diabetes at the time of their visit and may need to have other tests, such as:
- Laboratory tests: blood lipids, liver and kidney function, routine urine, etc.
- Special tests: fundus examination, electrocardiogram, neuropathy-related tests, urinary albumin excretion rate, ultrasonography of carotid and lower limb arteries