Blood glucose, or blood sugar, is the body’s primary energy source, derived from the food we consume. Glucose fuels every cell and organ, and its regulation is managed by the hormone insulin. Monitoring blood glucose levels is important because chronically elevated levels can signal a risk for developing metabolic conditions. This article clarifies what a blood sugar reading of 105 milligrams per deciliter (mg/dL) signifies by providing the necessary medical context for its interpretation.
Testing Context Matters
Interpreting a blood glucose reading of 105 mg/dL depends entirely on the conditions under which the blood sample was collected. The two most common scenarios are the Fasting Plasma Glucose (FPG) test and a random test. The FPG test requires no caloric intake for at least eight hours prior to the blood draw, providing a baseline measurement of how effectively the body controls glucose overnight.
A random glucose test can be taken at any time, regardless of the last meal. A single random reading of 105 mg/dL is generally not concerning, especially if several hours have passed since eating. However, this value carries a more significant implication if it was obtained after fasting, as the test conditions determine the medical classification applied to the result.
Classifying Blood Sugar Levels
Medical guidelines categorize Fasting Plasma Glucose (FPG) levels into distinct ranges. A reading is considered normal if it is below 100 mg/dL. Levels in this range indicate that the body is managing glucose effectively.
A fasting result of 105 mg/dL falls into the second category, known as Impaired Fasting Glucose (IFG), which is a classification of prediabetes. This range includes FPG values from 100 mg/dL to 125 mg/dL. A result of 105 mg/dL is not normal, but rather a sign that glucose regulation is beginning to falter.
This classification suggests that the body’s cells are becoming less responsive to insulin, a condition called insulin resistance. Impaired Fasting Glucose signifies a higher risk of progressing to type 2 diabetes and developing cardiovascular disease. An FPG reading of 126 mg/dL or higher, confirmed by repeat testing, is the diagnostic threshold for overt diabetes.
Next Steps After a Borderline Reading
A borderline fasting reading of 105 mg/dL warrants further medical evaluation, beginning with confirmatory testing. A physician will typically order an A1C test, which measures the average blood sugar level over the preceding two to three months. A prediabetes diagnosis is confirmed if the A1C falls between 5.7% and 6.4%.
The Oral Glucose Tolerance Test (OGTT) is another common test, measuring blood glucose two hours after consuming a standardized sugary drink. A two-hour result between 140 mg/dL and 199 mg/dL indicates Impaired Glucose Tolerance, another form of prediabetes. These tests help determine the severity of glucose intolerance and guide the intervention strategy.
Initial management for Impaired Fasting Glucose focuses on lifestyle modifications. Losing 5% to 7% of initial body weight can substantially reduce the risk of developing type 2 diabetes; for example, a 200-pound person losing 10 to 14 pounds. Physical activity should include at least 150 minutes of moderate-intensity aerobic exercise per week, such as brisk walking. Dietary changes should focus on reducing refined sugars and increasing fiber-rich foods like vegetables and whole grains. These actions improve insulin sensitivity and often allow glucose levels to return to the normal range.