What test is needed to diagnose diabetes?

This is an automatically translated article.

The article was written by MSc Do Thi Hoang Ha - Doctor of Biochemistry, Laboratory Department - Vinmec Hai Phong International General Hospital.
Complications of diabetes mellitus (DM) occur sooner or later depending on the type of disease and the process of accurate diagnosis, treatment and control of the disease. There are two types of complications of diabetes: acute (excessive hyperglycemia/hypoglycemia, ketoacidosis) and chronic (dyslipidemia, damage to small and large blood vessels, and some skin complications. , respiration, digestion ..).

So, to help doctors diagnose diabetes, come up with a suitable treatment plan, what tests will be recommended to apply?

1.Type I diabetes

Disease markers are 5 types of diabetes-associated autoantibodies (DAAs) that can be encountered, which are:
GADA autoantibodies (glutamic acid decarboxylase antibodies, mainly GADA65); islet cell autoantibodies (ICA); Autoantibodies against insulin tyrosine phosphatase-associated protein 2 (IA-2) autoantibodies (tyrosine phosphatase-like insulinoma associated protein 2 autoantibodies: IA-2); Anti-insulin autoantibodies (insulin autoantibodies: IAA); Antibodies against zinc transporter (Zinc transporter autoantibodies: ZnT8). Nearly 90% of people with type 1 diabetes have one or more of these antibodies at the time of diagnosis. Patients with type 2 diabetes have low or undetectable levels of these substances.
In general, autoantibodies to ICA, IAA, IA-2A, and ZnT8 are common in childhood-onset autoimmune diabetes, while GADA and IA-2A autoantibodies, especially GADA, are common in Type I diabetes has a later onset.

These antibodies may appear several years before symptom onset. Approximately 60–80% of patients with a positive test for insulin-resistant autoantibodies or pancreatic islet cells will develop insulin-dependent diabetes within 10 years, of which the GADA65 test provides definitive evidence. Diagnosis of type I diabetes as well as distinguishing between type I and type II diabetes (in patients with late-onset type I diabetes may cause confusion between type I and type II diabetes).
However, there are some caveats when using autoimmune antibodies in the diagnosis of type I diabetes, that is, the tests can be affected if within 7 days before the test the patient has used these drugs. radioisotopes as well as autoimmune antibodies detected in children are not the same as in adults. More than 50% of patients with type I diabetes are positive for insulin resistance (IAA) while most are negative in adults.
Patients who have been treated with insulin may also develop exogenous insulin resistance (IAA). The test cannot help doctors distinguish between these nascent antibodies and autoimmune antibodies, so it is not recommended for patients already on insulin therapy.
In addition, antibodies against pancreatic islet cells ICA can also be found in people with endocrine disorders such as Hashimoto's thyroiditis or Addison's disease.

2.Diabetes Type 2

To help clinicians make a definitive diagnosis of type II diabetes, the following tests are preferred in turn, as well as in combination with associated risk factors (age ≥ 45 years, obesity, have a family history of type II diabetes, have underlying comorbidities such as hypertension, metabolic syndrome, etc.).
Quantification of fasting serum / plasma glucose: This is the first test in the tests to help clinicians orient and make a diagnosis of diabetes. If the patient is tested for fasting blood sugar (after 8 hours of eating) ≥ 126 mg/dl (≥ 7.0 mmol/l) in 2 consecutive tests at least 24 hours apart, then it is considered diabetes. Quantification of serum/plasma glucose at any time: Any venous blood glucose ≥11.1 mmol/l accompanied by classic symptoms: excessive thirst, increased drinking, frequent urination, weight loss. Oral glucose tolerance test: Blood glucose after 2 hours of oral glucose tolerance test ≥11.1 mmol/l. HbA1c: The patient is diagnosed with diabetes if the HbA1c concentration is ≥ 6.5% (tested by standardized NGSP method). Especially for the Fasting Serum/Plasma Glucose Quantitative tests, Oral Glucose Tolerance Test and HbA1c should have at least one criterion performed 2 times 24 hours apart or 2 of the above criteria. same blood sample.

3. Gestational diabetes

Gestational diabetes often has no symptoms, so a glucose tolerance test should be done.
In the glycemic tolerance test for pregnant women (weeks 24-28 of pregnancy):
+ First time glucose: < 5.3 mmol/l.
+ Second glucose: < 10.1 mmol/l.
+ Glucose for the third time: < 8.6 mmol/l.
According to the standards of the International Association of Diabetes and Pegnancy Study Groups (IADPSG) and the American Diabetes Association (ADA):
+ If blood glucose When fasting > 7.0 mmol/l, the pregnant woman has clinical diabetes.
+ If one or more of the parameters in all 3 times is greater than the above value, it is gestational diabetes.
+ In normal pregnant women, all 3 parameters are smaller than the values ​​mentioned above.
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