What is the Normal Range for Fasting Blood Sugar Levels?

The fasting plasma (or serum) glucose level for adults should be 3.9 to 6.1 mmol/L. If the fasting glucose level is less than 3.9 mmol/L, it is considered hypoglycemia for diabetic patients; for healthy individuals, if the fasting glucose level is less than 2.8 mmol/L, it is also called hypoglycemia. However, if the fasting glucose level is greater than 6.1 mmol/L but less than 7.0 mmol/L, it is known as impaired fasting glucose, which is an early indicator of diabetes. If the fasting glucose level is greater than or equal to 7.0 mmol/L, it may indicate diabetes, and further glucose tolerance testing is needed. If the fasting glucose level is greater than 7.0 mmol/L on two occasions, diabetes can be diagnosed directly.

For healthy individuals, the normal fasting glucose level in the morning is between 3.89 and 6.1 mmol/L. If the fasting glucose level is greater than 6.1 mmol/L but less than 7.0 mmol/L, it suggests impaired fasting glucose. If the fasting glucose level is greater than or equal to 7.0 mmol/L on two occasions, diabetes should be considered. In such cases, it is recommended to repeat the fasting glucose test and undergo glucose tolerance testing. Additionally, a random glucose level greater than or equal to 11.1 mmol/L can confirm a diagnosis of diabetes. If the glucose level falls below 2.8 mmol/L, the corresponding clinical symptoms are referred to as "hypoglycemia".

It is recommended to test fasting glucose levels in the morning, preferably between 6 am and 7 am, as this provides a clear indication of pancreatic function. Before undergoing a fasting glucose test, it is essential to ensure that the stomach has been empty for 8 to 12 hours, meaning no food or water should be consumed after 10 pm the previous night. Adequate sleep is also crucial to prevent factors such as sleep deprivation, excessive food intake the previous day, or emotional arousal or vigorous activity before the test, which can all lead to elevated blood sugar levels.

Diabetes is often caused by unhealthy dietary habits, including smoking, alcohol consumption, binge eating, and a high-fat diet, which are all risk factors that can exacerbate the condition. To better control blood sugar levels, it is essential to be mindful of dietary intake, opting for lighter meals and incorporating more vegetables and whole grains into the diet, as these are beneficial for stabilizing blood sugar. Additionally, obese individuals have a higher risk of developing diabetes compared to those with a normal weight, so maintaining a healthy weight is crucial. Especially for those with a body weight exceeding the normal range, engaging in regular exercise to reduce weight and maintain a healthy weight range is essential for diabetes prevention.