Understanding High Blood Sugar Levels and Diabetes Diagnosis

High blood sugar, or hyperglycemia, typically refers to fasting blood glucose levels above 5.6 mmol/L or post-meal (two hours after eating) blood glucose levels exceeding 7.8 mmol/L. These values serve as early indicators that prompt further investigation into potential glucose metabolism issues.

Criteria for Diagnosing Diabetes

To receive a formal diabetes diagnosis, specific thresholds must be met. A fasting blood glucose level of 7.0 mmol/L or higher, a random blood glucose reading of 11.1 mmol/L or more, or a two-hour blood glucose level of 11.1 mmol/L during an oral glucose tolerance test (OGTT) are all diagnostic markers for diabetes. However, these measurements must be accompanied by noticeable symptoms of elevated blood sugar, such as excessive thirst, frequent urination, or unexplained fatigue.

Confirming the Diagnosis

If symptoms are not present, healthcare professionals typically require at least two separate blood tests showing abnormal results to confirm a diabetes diagnosis. It's important to note that normal fasting blood sugar levels do not completely rule out diabetes. Some individuals may experience elevated post-meal glucose levels, which can be an early sign of the condition—particularly in type 2 diabetes.

The Importance of Post-Meal Blood Sugar Testing

This pattern of isolated postprandial hyperglycemia is common in the early stages of type 2 diabetes. As a result, monitoring blood glucose two hours after meals is a crucial diagnostic tool that should not be overlooked. It provides a more comprehensive view of how the body processes sugar throughout the day, beyond what fasting levels alone can reveal.

Special Considerations for At-Risk Individuals

For individuals with fasting blood glucose levels above 5.6 mmol/L and those who are overweight or obese, it is strongly recommended to undergo a 75g oral glucose tolerance test. This test helps identify impaired glucose tolerance, which may not be detectable through fasting tests alone, and allows for early intervention to prevent the progression to full-blown diabetes.