What is the Ideal Time for Measuring Fasting Blood Sugar?

Everyone knows that it is best to do a fasting blood sugar test for accurate results. However, many people do not fully understand what fasting means. Fasting for a blood sugar test refers to the condition where the person being tested has not eaten any food after a full night's sleep and performs the test in the morning. This ensures that the results accurately reflect the function of the pancreatic islet cells.

1. What is the best time for fasting blood sugar measurement?

The optimal time for fasting blood sugar measurement is around 6 to 7 am. However, hospitals typically open after this time, so some patients may end up having their blood sugar tested at 9 am after completing registration, consultation, and payment procedures. Blood sugar levels measured at 9 am may be higher than those measured at 7 am, leading to the illusion that hospital fasting blood sugar values are higher than those measured at home.

Additionally, even if diabetic patients do not eat any food in the morning, their blood sugar levels will gradually rise. Therefore, it is recommended that individuals who wish to measure their fasting blood sugar do so earlier in the morning as later measurements may yield less accurate results. If a patient waits until 10 or even 11 am to have their fasting blood sugar tested at the hospital, the results may not be accurate.

2. The significance of fasting blood sugar

After a night's rest, fasting blood sugar can reflect the body's own insulin secretion level, which represents the basal insulin secretion status of the human body. Additionally, as the body prepares for the new day's work and activities, hormones that raise blood sugar levels, such as growth hormone and adrenaline, begin to increase regularly in the early morning. People with diabetes may have decreased basal insulin secretion, leading to increased morning blood sugar levels. Furthermore, fasting blood sugar can also reflect the absorption of the previous evening's dinner. By monitoring blood sugar levels, individuals can gain insights into their dietary habits and make necessary adjustments to prevent blood sugar spikes.

In summary, fasting blood sugar measurements can help individuals with diabetes understand their glycemic control and make timely adjustments.

3. Normal fasting blood sugar levels

Generally, fasting whole blood sugar levels range from 3.9 to 6.1 mmol/L (70 to 110 mg/dL), and plasma glucose levels range from 3.9 to 6.9 mmol/L (70 to 125 mg/dL). If fasting whole blood sugar levels are ≥6.7 mmol/L (120 mg/dL) or plasma glucose levels are ≥7.8 mmol/L (140 mg/dL), a repeat measurement can confirm a diagnosis of diabetes.