Diabetes Mellitus describes several diseases of abnormal carbohydrate
metabolism that are featured with hyperglycemia. It is related with a relative
or absolute impairment in insulin secretion, along with different degrees of
peripheral resistance to the action of insulin.
Diagnostic Criteria for Diabetes Mellitus
1. According to WHO criteria, the diagnosis of Diabetes Mellitus can be
easily established when a patient presents with classic symptoms of
hyperglycemia (polyuria, polydipsia, and unexplained weight loss) plus
a random venous plasma glucose concentration > 11.1 mmol/l
or
a fasting plasma glucose concentration > 7.0 mmol/l (whole blood >
6.1mmol/l)
or
two hour plasma glucose concentration > 11.1 mmol/l two hours after 75g
anhydrous glucose in an oral glucose tolerance test (OGTT).
2. With no symptoms diagnosis should not be based on a single glucose
determination but requires confirmatory plasma venous determination. At least
one additional glucose test result on another day with a value in the diabetic
range is essential, either fasting, from a random sample or from the two hour
post glucose load. If the fasting or random values are not diagnostic the two
hour value should be used.
3. WHO Recommendation 2011
HbA1c can be used as a diagnostic test for Diabetes providing that stringent
quality assurance tests are in place and assays are standardised to criteria
aligned to the international reference values, and there are no conditions
present which preclude its accurate measurement.
An HbA1c of 48 mmol/mol (6.5%) is recommended as the cut point for diagnosing
diabetes. A value of less than 48 mmol/mol (6.5%) does not exclude diabetes
diagnosed using glucose tests.
Cases where HbA1c is not proper for diagnosis of Diabetes Mellitus:
● ALL children and young people.
● Patients of any age suspected of having Type 1 diabetes.
● Patients with symptoms of diabetes for less than 2 months.
● Patients at high diabetes risk who are acutely ill.
● Patients taking medication that may cause rapid glucose rise.
● Patients with acute pancreatic damage, including pancreatic surgery.
● In pregnancy.
● Presence of genetic, haematologic and illness-related factors that
influence HbA1c and its measurement.