How is hypoglycemia diagnosed?

Many people are found to experience hypoglycemia in daily life. Although it is not a serious illness, untreated hypoglycemia can still pose significant health risks and therefore requires prompt medical evaluation at a hospital. So, how is hypoglycemia diagnosed?

How Is Hypoglycemia Diagnosed?

The most reliable method for diagnosing hypoglycemia is to undergo clinical testing at a hospital, including a complete blood count (CBC), biochemical assays, and plasma insulin measurement. These tests help confirm whether hypoglycemia is present. Patients with diabetes may also develop hypoglycemia after taking antidiabetic medications—even without obvious symptoms—and should therefore monitor their blood glucose levels in a clinical setting to assess for diabetes. A diagnosis of hypoglycemia is established when fasting blood glucose falls below 2.8 mmol/L and is accompanied by characteristic hypoglycemic symptoms, necessitating timely treatment.

Additionally, patients may perform a self-administered fasting test. For example, after eating dinner at 6–7 p.m., no further caloric intake is allowed. The fast continues until the following morning at 6–7 a.m., resulting in a 12-hour fasting test to assess for hypoglycemic episodes. If no hypoglycemia occurs, the fasting period may be extended—for instance, up to noon the next day (i.e., a 16-hour fast). If no hypoglycemia manifests after 16 hours, hypoglycemia is unlikely.

Some hospitals may extend the fasting test to 20 hours to improve detection of hypoglycemia. If hypoglycemia occurs during the fasting test, simultaneous measurements of blood glucose and insulin are required to calculate the insulin secretion index. An abnormal index suggests dysregulated insulin release; if the index is normal, an insulinoma (insulin-secreting pancreatic neuroendocrine tumor) should be considered. We hope this information proves helpful to you.