How is diabetes diagnosed ?

Diabetes (both type 1 and type 2) can be diagnosed or detected based on:
 
• Presence of symptoms

• Blood sugar estimation (in a laboratory or using a glucometer) can be done at different times and the 3 common time points are :

- Fasting Plasma Glucose (FPG)- testing blood sugar levels after 8 hours of fasting, usually overnight fasting
- Postprandial Plasma Glucose (PPG)- testing blood sugar levels 2 hours after a meal (usually it is breakfast)
- Random or casual sugar- any time of the day irrespective of meal intake

Refer table 1 for tests and interpretation of results.

• Oral Glucose Tolerance Test (OGTT) is a test done to confirm the diagnosis in doubtful cases (i.e. cases were FPG and/or PPG are in the borderline range).In this test one has to drink 75 gm glucose (sugar) in water on empty stomach and blood sugar is to be tested after 2 hours. The interpretation of the results is shown in table 2.

Urine sugar testing alone is not recommended for diagnosis.

Table 1 - The tests commonly done and their interpretation :

                       
Table 2 - OGTT and its interpretation

 NGT=Normal Glucose Tolerance; IFG= Impaired Fasting Glucose (Pre diabetes); IGT= Impaired Glucose Tolerance (Pre diabetes); DM= Diabetes Mellitus; 25-40% patients with IGT progress to DM
Urine sugar testing alone is not recommended for diagnosis.