Mother-Baby University

GLUCOSE METABOLISM

Of the principal foodstuffs--carbohydrates, fats and proteins--cells extract energy from the carbohydrates

Again, circulating glucose provides fuel to the body's tissues and is necessary for normal cellular metabolism

Essentially all carbohydrates in the human body are converted to glucose before entering the cells

Glucose is converted and utilized through the process of glycolysis

This can occur with or without oxygen (aerobic or anaerobic)

Anaerobic system requires more fuel to accomplish
glucose metabolism than aerobic system

Glucose not immediately required for fuel is converted to Glycogen and stored in the liver, heart and skeletal muscles

When oral intake is insufficient or absent, glycogen is released into the blood stream by the liver

Hepatic glycogen stores are limited so alternate
sources such as the non-carbohydrate sources—fats and proteins--are also used to produce glucose

Once inside the cells glucose reacts chemically with oxygen (along with various enzymes that control the cell's rate of reaction) and channels the release of energy

The energy released is used in the form of adenosine triphosphate (ATP)

Then ATP, not the original carbohydrate, is used throughout the cell to energize all the intracellular metabolic reactions

The need for glucose by the body is ongoing......but the need for glucose by the brain is constant

Dependent on glucose for its survival

Fortunately, the brain is able to oxidize glucose directly

Glucose plays a vital role in maintaining our life

The adult depends on him/herself for a glucose supply........they are independent

Supply may be variable, intermittent but oral intake (glucose supply) is generally easy to obtain and maintain

The fetus depends on the mother for glucose and other nutrients

Glucose diffuses across the placenta, providing a continuous supply in utero

Glycogen storage begins early in gestation with most accumulating in the third trimester

This is a concern for infants born prematurely

Insulin needed for fetal growth can be detected early in the pregnancy but its response to glucose changes, up or down, is limited even at term

The newborn as it transitions to extrauterine life must make major metabolic adjustments to achieve euglycemia since the placenta and its glucose supply are abruptly removed

Glucose Use By the Neonate

When the infant is delivered:

The newborn's blood glucose at birth reflects approximately 70-80% of the mother's level

Glucose supply is consumed and its level falls fairly rapidly as the newborn transitions to extra-uterine life

Reaches nadir* at about 1-3 hours after birth

PLASMA glucose concentration of < 35 mg/dL during this time should be of concern

During these first 1-3 hours, the newborn usually has limited or no oral intake and recognizes the situation as "starvation"

To meet the high metabolic demands the body's plasma glucagon level, along with other hormonal changes, rises

Triggers the release of glycogen from the liver

Initiates the production of glucose

Results in increased plasma blood glucose levels

90% of the glycogen stores present at birth are converted by 3 hours of age

It will take several days for the average, non-stressed newborn to reach and maintain its baseline blood glucose levels

The infant's ability to respond is influenced by:

Mother's last meal

Duration of labor

Premature/Low birthweight infants may not be able to respond effectively

Increased glucose need and use

Lack of glycogen stores

Immature ability to produce glucose

Simultaneous illnesses such as sepsis, pulmonary disease, thermal stress

Exposure to maternal medications

Type of delivery (vaginal vs. Cesarean)

Type and volume of maternal IV fluids during labor and delivery

*nadir: lowest point

The nurse caring for the newborn needs to be alert to the signs and symptoms of abnormal serum glucose levels

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GLUCOSE METABOLISM

Glucose Use By the Neonate