Blood sugar, or glucose, is the primary source of energy for the body’s cells. Maintaining balanced glucose levels is fundamental to metabolic health. A measurement of 135 milligrams per deciliter (mg/dL) prompts questions about whether the level is too high. Understanding this number requires context about when the measurement was taken and how it compares to established health guidelines.
Understanding Different Blood Sugar Measurements
Interpreting a blood sugar reading depends entirely on the circumstances surrounding the test. Medical professionals use three primary measurement states to assess glucose control. The fasting plasma glucose (FPG) test is taken after a person has not consumed calories for at least eight hours, usually in the morning. The two-hour postprandial measurement, often called the Oral Glucose Tolerance Test (OGTT), assesses how the body processes sugar after a meal or standardized sugary drink. This test checks the body’s insulin response to a glucose load. The random plasma glucose (RPG) test is taken at any time of day, regardless of when the person last ate. Because glucose levels naturally fluctuate, each condition has distinct target ranges. Defining the measurement condition is the necessary first step before any interpretation can be made.
Interpreting a 135 mg/dL Reading
A blood sugar level of 135 mg/dL falls into different diagnostic classifications depending on the testing condition.
Fasting Plasma Glucose (FPG)
If 135 mg/dL is a fasting measurement, it is considered elevated. Normal fasting glucose is below 100 mg/dL, and 100 to 125 mg/dL is classified as prediabetes (impaired fasting glucose). A fasting reading of 135 mg/dL is above the prediabetes range and meets the threshold for a preliminary diagnosis of diabetes (126 mg/dL or higher). This suggests the body is not effectively managing glucose without food intake. However, a single test result is insufficient for a definitive diagnosis, and a repeat test is necessary for confirmation.
Two-Hour Postprandial
If 135 mg/dL was taken two hours after eating, the interpretation is much less concerning. For non-diabetic individuals, the two-hour postprandial level is considered normal if it is below 140 mg/dL. In this context, 135 mg/dL is within the healthy range, indicating an appropriate insulin response to the meal.
Random Plasma Glucose (RPG)
If 135 mg/dL was a random test taken at an unspecified time, it is not high enough for an immediate diabetes diagnosis. A random measurement suggesting diabetes is 200 mg/dL or higher. Although 135 mg/dL falls below this threshold, it is still elevated enough to warrant follow-up testing, especially if risk factors are present.
Common Factors That Affect Blood Sugar Levels
A single elevated blood sugar measurement is not always a permanent reflection of metabolic health. Numerous transient factors can temporarily raise glucose levels. Physical stress, such as recovering from surgery, injury, or acute illness, triggers the release of stress hormones like cortisol and epinephrine. These hormones signal the liver to release stored glucose, causing a temporary spike in readings. Acute emotional stress or lack of sleep can also elevate glucose through a similar hormonal mechanism. Certain prescription medications can interfere with glucose processing; for instance, corticosteroids are known to induce insulin resistance. Additionally, a recent meal high in refined carbohydrates will naturally elevate glucose if the measurement was taken less than two hours after eating. These temporary causes highlight why a diagnosis requires more than one abnormal test result.
Recommended Follow-Up Actions
A reading of 135 mg/dL, especially if it was a fasting or random test, should prompt a consultation with a healthcare provider. The next step is to confirm the result with a repeat test, such as a second fasting plasma glucose test, to rule out temporary fluctuations. A provider will likely order a Hemoglobin A1C test, which provides a long-term average of blood sugar control over the previous two to three months. The A1C test is a valuable tool because it is not affected by short-term factors like a recent meal or acute stress. While waiting for medical guidance, a person can adopt initial lifestyle adjustments to support healthy glucose management. Increasing physical activity, such as aiming for 30 minutes of moderate exercise most days, helps cells become more sensitive to insulin. Focusing on a balanced diet that limits highly processed foods and sugary beverages helps stabilize glucose levels. Ensuring adequate hydration is beneficial, as dehydration can concentrate blood sugar. These steps can help improve metabolic function and provide a clearer picture for the healthcare team when follow-up tests are performed.