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Normal Glucose Levels Chart: An Overview
Normal Fasting Plasma Glucose Levels
Fasting plasma glucose (FPG) levels are a critical measure for assessing glucose homeostasis and potential diabetes risk. The normal fasting plasma glucose level is defined as less than 100 mg/dL (5.55 mmol/L). However, even within this normal range, higher fasting plasma glucose levels can predict an increased risk of type 2 diabetes. For instance, men with fasting plasma glucose levels of 87 mg/dL (4.83 mmol/L) or more have a progressively increased risk of developing type 2 diabetes compared to those with levels below 81 mg/dL (4.5 mmol/L).
24-Hour Plasma Glucose Values
Throughout a 24-hour period, arterial plasma glucose values average around 90 mg/dL, with fluctuations depending on activities such as eating and exercise. Post-meal glucose levels can peak at approximately 165 mg/dL, while levels can drop to around 55 mg/dL after exercise or moderate fasting. This stability contrasts with other metabolic substrates like glycerol and lactate, which exhibit wider fluctuations.
Glucose Tolerance in Children and Adolescents
In both adults and children, normal fasting blood sugar levels range between 70 and 110 mg/dL. These levels show minimal fluctuation over time, indicating stable glucose homeostasis. For infants, blood glucose levels can initially range from 1.4 to 6.2 mmol/L (25 to 112 mg/dL) but stabilize to normal values (3.5-5.5 mmol/L or 63-99 mg/dL) within 72 hours after birth.
Continuous Glucose Monitoring (CGM) Metrics
Continuous glucose monitoring (CGM) provides detailed insights into glucose levels throughout the day. In healthy individuals without diabetes or prediabetes, CGM data show that median time spent in the normal glucose range (70-180 mg/dL) is about 97.3%, with minimal time spent in hypoglycemia (<70 mg/dL). This data is crucial for understanding normal glucose profiles and setting benchmarks for clinical practice and glucose-lowering trials.
Glucose Tolerance and Beta-Cell Function in Obese Youth
Normal glucose tolerance spans a wide range of glucose concentrations. In obese youth, even within the normal range, higher 2-hour plasma glucose levels after an oral glucose tolerance test are associated with impaired beta-cell responsiveness, independent of insulin resistance. This suggests a continuum of risk for developing type 2 diabetes even when glucose levels are considered normal.
Neonatal Hypoglycemia Thresholds
Defining low plasma glucose thresholds in newborns is essential for early detection and management of hypoglycemia. In full-term normal newborns, the 5th percentile thresholds for plasma glucose are ≤28 mg/dL during the first 1-2 hours, ≤40 mg/dL from 3-23 hours, and ≤48 mg/dL from 24-72 hours after birth. These thresholds help in identifying and managing neonatal hypoglycemia effectively.
Conclusion
Understanding normal glucose levels and their variations across different age groups and conditions is vital for early detection and management of glucose-related disorders. Fasting plasma glucose levels, 24-hour glucose profiles, and CGM metrics provide comprehensive insights into glucose homeostasis, helping to identify individuals at risk for diabetes and other metabolic conditions.
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