Normal blood glucose levels
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Understanding Normal Blood Glucose Levels
Definition and Importance of Blood Glucose Levels
Blood glucose levels refer to the concentration of glucose present in the blood, which is a critical measure for maintaining energy balance and overall health. Normal blood glucose levels are essential for proper metabolic function and are tightly regulated by various hormones, including insulin, glucagon, and cortisol 2.
Normal Blood Glucose Ranges
Fasting Blood Glucose Levels
Fasting blood glucose levels are measured after an individual has not eaten for at least 8 hours. The normal range for fasting blood glucose is typically between 70 and 130 mg/dL (3.9 to 7.2 mmol/L) 34. More specifically, a fasting blood glucose level of less than 100 mg/dL (5.55 mmol/L) is considered normal 17.
Postprandial Blood Glucose Levels
Postprandial blood glucose levels are measured after eating. Normally, blood glucose levels rise after a meal and should be less than 140 mg/dL (7.8 mmol/L) within two hours after eating 4. For pregnant women, the postprandial peak glucose value is around 110 mg/dL, with the peak occurring approximately 70 minutes after a meal 6.
Diurnal Variations
Throughout a 24-hour period, blood glucose levels can fluctuate. Typically, arterial plasma glucose values average around 90 mg/dL, with a maximum concentration not exceeding 165 mg/dL after meals and remaining above 55 mg/dL after exercise or moderate fasting 5.
Blood Glucose Levels in Different Life Stages
Neonates and Infants
In newborns, blood glucose levels can vary significantly shortly after birth. For the first few hours of life, normal blood glucose levels range between 1.4 and 6.2 mmol/L (25 to 112 mg/dL). By 72 hours of age, these levels stabilize to the normal range seen in infants, children, and adults, which is 3.5 to 5.5 mmol/L (63 to 99 mg/dL) 2. In a study of healthy newborns, the median glucose concentration was found to be 58 mg/dL within the first few hours after birth 10.
Young Adults
In young adults, fasting plasma glucose levels within the normal range can still predict the risk of developing type 2 diabetes. For instance, men with fasting plasma glucose levels of 87 mg/dL (4.83 mmol/L) or more have an increased risk of developing type 2 diabetes compared to those with lower levels 1. Similarly, individuals with fasting plasma glucose levels of 95 to 99 mg/dL are significantly more likely to develop diabetes compared to those with levels below 85 mg/dL 7.
Factors Influencing Blood Glucose Levels
Diet and Lifestyle
Diet and regular physical activity play crucial roles in maintaining normal blood glucose levels. Carbohydrates are the primary source of glucose, and a balanced diet helps in regulating blood sugar levels. Regular exercise also helps in lowering blood glucose levels, improving muscle power, and maintaining overall metabolic health 3.
Hormonal Regulation
The regulation of blood glucose levels is a complex process involving several hormones. Insulin lowers blood glucose levels by facilitating the uptake of glucose into cells, while glucagon increases blood glucose levels by promoting the release of glucose from the liver. Other hormones like epinephrine, norepinephrine, cortisol, and growth hormone also play roles in glucose homeostasis 2.
Conclusion
Maintaining normal blood glucose levels is vital for overall health and the prevention of metabolic disorders such as diabetes. Understanding the normal ranges for fasting and postprandial blood glucose levels, as well as the factors that influence these levels, can help individuals manage their health more effectively. Regular monitoring and a balanced lifestyle are key to maintaining optimal blood glucose levels.
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Most relevant research papers on this topic
Normal fasting plasma glucose levels and type 2 diabetes in young men.
Higher fasting plasma glucose levels within the normal range are an independent risk factor for type 2 diabetes in young men, and may help identify seemingly healthy men at increased risk for diabetes.
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Normal Glucose Homeostasis
Normal glucose homeostasis maintains a stable blood sugar level, with a maximum concentration not exceeding 165 mg/dl after meal ingestion and a minimum concentration remaining above 55 mg/dl after exercise or a moderate fast (60 h).
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