How Do I Make the Diagnosis of Diabetes?

Case Study

Mrs. HR is a 48 year old whom you have screened for diabetes since she is over 40, and has a family history of diabetes.

You decided to use the A1C test.

  • Her first A1C comes back 6.5%

Should you tell her she has Type 2 diabetes?

Yes No
Reveal Answer

You are correct!

Mrs. HR’s first result is in the diabetes range, however, "a repeat confirmatory laboratory test must be done on another day".

Click here to review the Diagnostic Criteria for Diabetes.

Mrs. HR goes for a repeat A1C early the following week.

Her next A1C is 6.9% - the diagnosis of Type 2 Diabetes is confirmed.

No, not yet.

Mrs. HR’s first result is in the diabetes range, however, "a repeat confirmatory laboratory test must be done on another day".

Click here to review the Diagnostic Criteria for Diabetes.

Mrs. HR goes for a repeat A1C early the following week.

Her next A1C is 6.9% - the diagnosis of Type 2 Diabetes is confirmed.

2018 Diabetes Canada Diagnostic Criteria for Diabetes

FPG ≥ 7.0 mmol/L
Fasting = no caloric intake for at least 8 hours

or

A1C ≥ 6.5% (in adults)
Using a standardized, validated assay in the absence of factors that affect the accuracy of the A1C and not for suspected type 1 diabetes (see text)

or

2hPG in a 75-g OGTT ≥ 11.1 mmol/L

or

Random PG ≥ 11.1 mmol/L
Random = any time of the day, without regard to the interval since the last meal

In the absence of symptomatic hyperglycemia, if a single laboratory test result is in the diabetes range, a repeat confirmatory laboratory test (FPG, A1C, 2hPG in a 75 g OGTT) must be done on another day. It is preferable that the same test be repeated (in a timely fashion) for confirmation, but a random PG in the diabetes range in an asymptomatic individual should be confirmed with an alternate test. In the case of symptomatic hyperglycemia, the diagnosis has been made and a confirmatory test is not required before treatment is initiated. If results of 2 different tests are available and both are above the diagnostic thresholds, the diagnosis of diabetes is confirmed.

To avoid rapid metabolic deterioration in individuals in whom type 1 diabetes is likely (younger or lean or symptomatic hyperglycemia, especially with ketonuria or ketonemia), the initiation of treatment should not be delayed in order to complete confirmatory testing.

2hPG, 2-hour plasma glucose; AlC, glycated hemoglobin; FPG, fasting plasma glucose; OGTT, oral glucose tolerance test; PG, plasma glucose.


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