Fasting glucose provides a snapshot of the sugar, or glucose, in your bloodstream after a period of not eating or drinking. This common metabolic health screening tool offers a baseline understanding of how your body manages blood sugar when not processing food. This reading helps healthcare providers assess your body’s ability to regulate glucose, a primary source of energy for your cells.
The Fasting Glucose Test
To prepare for a fasting glucose test, you must abstain from all food and beverages, except for water, for at least eight to twelve hours beforehand. This ensures the measurement reflects your baseline glucose level, not a spike from a recent meal. For this reason, the test is often scheduled in the morning.
A healthcare professional will draw a small sample of blood, usually from a vein in your arm. The test can also be performed with a small drop of blood from a finger prick. The collected sample is then sent to a laboratory for analysis to determine the concentration of glucose.
Interpreting Your Results
The results are reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L), depending on the country. A result below 100 mg/dL (5.6 mmol/L) is considered normal. This indicates that your body is effectively managing its blood sugar levels during a fasting state.
A reading between 100 and 125 mg/dL (5.6 to 6.9 mmol/L) is classified as prediabetes. This result suggests your blood sugar is higher than normal but has not reached the threshold for a diabetes diagnosis, indicating your body’s ability to handle glucose is becoming compromised.
A fasting glucose level of 126 mg/dL (7.0 mmol/L) or higher on two separate occasions indicates diabetes. An elevated reading will likely prompt your healthcare provider to recommend additional testing, such as an A1c test which reflects your average blood sugar over two to three months, to confirm a diagnosis and get a more complete picture of your glucose control.
Factors That Influence Fasting Glucose
A primary driver of elevated fasting glucose is insulin resistance. With this condition, cells in your muscles, fat, and liver don’t respond well to insulin, the hormone that helps glucose enter cells for energy. This lack of response causes glucose to build up in the blood.
Another contributor is the “dawn phenomenon,” a natural surge of hormones like cortisol and growth hormone in the early morning hours. These hormones can trigger the liver to release more glucose into the bloodstream, raising levels upon waking.
Acute illnesses or infections can cause a temporary stress response in the body, leading to higher glucose production. Chronic psychological stress elevates cortisol levels, which can interfere with insulin’s effectiveness over time. Poor or insufficient sleep also negatively impacts insulin sensitivity and fasting glucose.
Managing Fasting Glucose Levels
Dietary adjustments that prioritize whole, unprocessed foods can help manage fasting glucose. Emphasizing foods high in fiber, such as vegetables, legumes, and whole grains, helps to slow down sugar absorption and improve blood sugar control. Limiting the intake of refined carbohydrates and sugary beverages is also a direct way to reduce the glucose load on your body.
Regular physical activity helps manage glucose levels by enhancing the body’s sensitivity to insulin, allowing your cells to use available glucose more efficiently. Both aerobic exercises, like brisk walking or cycling, and resistance training, such as lifting weights, contribute to better glucose uptake by the muscles.
Addressing sleep and stress is also part of a management plan. Aiming for seven to nine hours of quality sleep per night can help regulate the hormones that influence blood sugar. Incorporating stress-management techniques, such as mindfulness or yoga, can help lower cortisol levels and improve insulin function. Always consult a healthcare professional for personalized guidance before making significant changes to your health regimen.