Blood glucose, often called blood sugar, is the primary sugar found in your blood, derived from the food you eat. It serves as the main energy source for your body’s cells and is carried to those cells via the bloodstream. The concentration of this sugar is measured in milligrams per deciliter, or mg/dL. A reading of 170 mg/dL is a specific measurement that prompts concern. This single number needs to be placed into a broader context to determine its significance for overall health.
Understanding Blood Sugar Ranges
The interpretation of any blood sugar reading depends heavily on the context of when the measurement was taken. Medical organizations define distinct ranges to help classify a person’s glucose status. A normal fasting plasma glucose level, taken after at least eight hours without food, is considered to be less than 100 mg/dL.
Readings that fall between 100 mg/dL and 125 mg/dL on a fasting test are classified as prediabetes, also known as impaired fasting glucose. Prediabetes indicates that blood sugar levels are elevated above the normal range but are not yet high enough to meet the criteria for a diabetes diagnosis. A fasting reading of 126 mg/dL or higher on two separate occasions is the threshold for a diagnosis of diabetes.
The post-meal or postprandial glucose level is typically taken one to two hours after eating. A blood sugar level measured two hours after a meal should be less than 140 mg/dL. Levels between 140 mg/dL and 199 mg/dL two hours after a meal indicate impaired glucose tolerance, a form of prediabetes. A two-hour post-meal level of 200 mg/dL or greater is a diagnostic threshold for diabetes.
Interpreting a 170 Reading
A blood sugar reading of 170 mg/dL is considered high and falls outside the target range for healthy individuals. If this value was measured while fasting, it is significantly above the 126 mg/dL threshold used to diagnose diabetes. Such a high fasting level indicates that the body is having difficulty controlling glucose even without new food intake.
If the 170 mg/dL reading was measured approximately two hours after a meal, it is above the normal post-meal target of under 140 mg/dL. This result places the measurement within the range for impaired glucose tolerance or prediabetes. The number points to the body’s reduced ability to process sugar effectively, suggesting potential insulin resistance or inadequate insulin production.
A reading of 170 mg/dL suggests that insulin is not working as efficiently as it should. This inefficiency can be due to the body’s cells not responding properly to insulin (insulin resistance), or because the pancreas is not producing enough of the hormone. Sustained periods of high glucose can cause damage to blood vessels and nerves over time. This reading warrants prompt medical investigation to determine the underlying cause and course of action.
Common Influencers of Elevated Glucose
Dietary intake is the most immediate factor influencing a blood sugar spike, particularly the consumption of high-carbohydrate foods like refined sugars and processed starches. These foods are broken down quickly into glucose, leading to a rapid influx into the bloodstream that may temporarily overwhelm the body’s ability to produce or use insulin. A meal exceptionally high in simple carbohydrates could push glucose levels to 170 mg/dL even in a person who is otherwise healthy.
Several physiological and lifestyle factors can cause a temporary elevation in blood glucose. Stress, whether emotional or physical, triggers the release of hormones like cortisol and epinephrine. These stress hormones are counter-regulatory, meaning they raise blood sugar levels to provide the body with energy to cope with the stressor.
Lifestyle and Physiological Factors
Lack of adequate sleep can impair insulin efficiency, making the body less effective at controlling blood sugar. Certain medications, such as corticosteroids used to reduce inflammation, are known to raise blood glucose as a side effect. Even common issues like dehydration or a mild infection can cause a temporary spike in glucose levels as the body releases stress hormones to fight the illness.
Seeking Follow-Up and Professional Advice
If a reading of 170 mg/dL is observed, contacting a healthcare provider is necessary, especially if the reading was taken while fasting or if multiple high readings have been recorded. A single high reading indicates a need for a professional evaluation. The provider will likely order more definitive diagnostic tests to assess long-term glucose control.
The A1C test is a standard follow-up, providing an average of blood sugar levels over the preceding two to three months. Since the A1C is not affected by recent meals or temporary spikes, it is used to diagnose prediabetes (5.7% to 6.4%) or diabetes (6.5% or higher). An oral glucose tolerance test (OGTT) may also be administered, which involves measuring blood glucose before and two hours after drinking a standardized sugary liquid.
The professional will recommend lifestyle adjustments to help bring glucose levels into a safer range. Regular physical activity helps muscles use glucose for energy, which improves insulin sensitivity. Focusing on a balanced diet with controlled carbohydrate portions and staying adequately hydrated are practical initial steps. These modifications are a first-line approach that can prevent or delay the progression to type 2 diabetes.