Diagnosis of hypoglycemia, especially recurrent hypoglycemia is not very difficult. Patient can understand he/she is having acute hypoglycemia from the symptoms of hypoglycemic attacks.
Hypoglycemia can also be established conclusively by documenting the Whipple’s triad: which include (1) consistency of symptoms (confusion, fatigue, behavioral changes, sweating, hunger, palpitations, tremor, anxiety etc.) with hypoglycemia, (2) low blood glucose level (precisely measured with right method and not by commonly used glucose monitor), (3) disappearance or relief of the above symptoms when blood glucose level is raised to normal.
Another way to diagnose hypoglycemia is by measuring blood glucose level below 55 mgs/100 ml (3.0 mmol/L) of blood with symptoms of mentioned above (all of the above mentioned symptoms seldom occurs in an individual with hypoglycemia and usually only few of the symptoms are present at a time) which are promptly relieved by raising blood glucose.
The most difficult part of the hypoglycemia is to find out the cause of hypoglycemia. To find out the cause of hypoglycemia it is important to collect blood during an episode of hypoglycemia for checking glucose level as fulfillment of Whipple’s triad is required to conclusively diagnose hypoglycemia.
If the cause of hypoglycemia is not clear additional measures should be taken to try to find out the cause. The additional measures should include insulin, C-peptide, and ethanol (alcohol) concentrations in blood, ideally blood sample taken during episode of hypoglycemic attack and before starting treatment of hypoglycemia like administration of glucose. The level of insulin secretagogues also should be checked to find out the cause of hypoglycemia. If it is not possible to collect blood at the time of hypoglycemic episode, it should be collected for checking blood levels of insulin, C-peptide, and ethanol, when a hypoglycemic episode would be expected like during fasting.