Glucose Balance and Imbalance - labsstudies

Glucose Balance and Imbalance

Glucose Balance and Imbalance

Glucose Balance 

  • Glucose balance can be considered in the following circumstances:

 1. Following glucose administration

  • Blood glucose levels rise after oral administration of glucose and absorption of glucose from the intestine.
  • This stimulates insulin secretion from the pancreatic islets.

 2. In the post-absorption state

  • When a person fasts overnight, the liver and insulin-dependent tissue (resting muscle and fat) show little glucose uptake.
  • The insulin-independent tissues (brain, blood cells, and renal medulla) continue to uptake glucose at a rate of 150-200g/day. The release of glucose from the liver maintains the blood glucose level.

 3. During exercise

  • The oxidation of fatty acids provides the majority of the energy for muscular contraction while at rest.
  • Exercise increases fatty acid uptake while also increasing glucose uptake and oxidation.
  • To compensate for this peripheral utilization, the liver releases glucose into the bloodstream, resulting in little change in blood glucose levels.

Insulin Secretion and Action

  • Insulin is synthesized as proinsulin, a polypeptide containing amino acid residues, in the -cells of the islets of Langerhans.
  • Insulin is the primary hormone involved in glucose metabolism in cells.
  • Glucose from the circulation enters the cells/tissues with the help of a hormone known as insulin.
  • Glucose is oxidized in cells to produce energy.
  • It maintains an appropriate sugar concentration in the plasma and cells/tissues.

Insulin influences not only sugar metabolism, but also:

  • Fats by increasing fat storage and stimulating lipogenesis (fat sparing effect)
  •  Proteins by directly stimulating protein synthesis.
  •  Potassium by assisting with intracellular potassium ion concentration maintenance.

Normal blood glucose levels are kept within a narrow range of 4.4 – 6.6 mmol/L (80 -120 mg/dl).

 Below that range is hypoglacemia, and above it is hyperglacemia.

The following factors govern this normal level of sugar balance:

  •  Amount collected
  •  Absorption rate from the GIT
  •  The ability of the liver to store glucose under the influence of insulin
  •  The ability of the liver to convert glycogen to glucose in response to glucagon.

Other hormones that influence glucose metabolism include:

  •  The hormone glucagon This hormone is produced by islet langerhans -cells.
  • When the blood glucose level falls below 4.5 mmol/l, it is released. Its primary action is to stimulate the liver’s breakdown of glycogen into glucose, which is then released into the bloodstream.
  •  Adrenaline stimulates glycogenolysis in the liver and muscles, which raises blood glucose levels.
  •  Pituitary growth hormone, which inhibits insulin action and raises blood glucose levels.
  • Adrenal glucocorticoids inhibit glucose utilization in muscle and fat.
  •  Gluconeogenesis in the liver is stimulated, resulting in an increase in blood glucose levels.

Glucose Metabolism Disorder

  • Diabetes mellitus is the most significant disruption in glucose metabolism.
  • Diabetes mellitus is a syndrome characterized by a relative or absolute insulin deficiency.
  • In these cases, the pancreas may fail to produce insulin, secrete insufficient hormone, or the body may fail to utilize the insulin.

If this situation persists, the following scenario will occur:

  •  In the absence of insulin, sugar cannot enter the tissues for metabolism and thus accumulates in the blood (in the intravascular space).  Hyperglycemia is an excess of glucose in the blood, which leads to diabetes mellitus.
  •  Excess sugar in the blood increases plasma osmolarity, causing water to leave the interstitial space and enter the intravascular space, resulting in excessive thirty.
  •  Without insulin, the sugar concentration in the blood will rise until the renal threshold is reached, at which point sugar (glucose) will begin to appear in the urine.
  • The presence of sugar in the urine is referred to as glycosuria.
  •  The presence of glucose in the renal filtrates causes osmotic diuresis, which causes a large amount of water to be lost.
  •  As a result, the individual will produce a large amount of urine, a condition known as polyuria.
  •  Polyuria causes a significant loss of potassium (K+), resulting in electrolyte imbalance.
  • Polydypsia is a condition in which excessive urination worsens thirst and causes excessive drinking.
  •  The patient becomes thirsty and dehydrated.
  •  Variations in blood glucose levels cause osmotic effects in the lens and humours of the eye. The result is blurred vision.


Glucose Imbalance 

The following are conditions that lead to Glucose Imbalance:

1. Hypoglycemia

  • Hypoglycemia is defined as low blood glucose level.
  • It is less common, but it can result from an islet cell tumor’s excessive insulin release or from a patient receiving too much insulin during therapy.
  • Some insulin-producing tumors (insulinoma) can also cause hypoglycemia.
  •  Hypoglycemia is frequently observed in diabetic patients who do not eat their meals on time.
  • It usually occurs during starvation, but can also be caused by excessive alcohol with poor food intake.

2. Hyperglycemia

  • It refers to having high blood glucose levels on a regular basis.
  • It is frequently caused by a lack of functional insulin from ineffective pancreatic beta islet cells.
  • There is a decrease in glucose uptake and metabolism when insulin is not present.
  • This leads to excessive glycogenolysis and glucose accumulation in the blood.
  • Diabetes mellitus develops if not controlled.
  • Excessive secretion of epinephrine, corticosteroids, glucagon, or thyroid hormones are also causes of hyperglycemia.


3. Ketoacidosis

  • Lack of glucose in tissues/cells for energy production due to insulin deficiency stimulates the body to seek an alternative source of energy.
  • Fats are another readily available alternative food substrate.
  • As a result, in the absence of insulin, there is increased fat breakdown (lipolysis) to produce the necessary energy.
  • Ketone bodies are formed when fatty acids are degraded in the liver.
  • Ketone bodies (B-hydroxybutyric acid and aceto-acetic acid) can be oxidized to produce energy in low concentrations; however, in the absence of insulin, the rate of ketone body production exceeds the rate of ketone body utilization, causing ketonaemia (hyperketonaemia).
  • Ketone bodies raise plasma osmolarity, causing cell dehydration and increased thirst.
  • Because they are acidic in nature, they interfere with the body’s pH balance mechanism. This can lead to severe ketoacidosis and, in some cases, ketoacidotic coma.

Effect of Glucose Imbalance

  • If the condition persists for a long time, a series of changes may occur due to the presence of high concentrations of glucose in the blood.

 Hyperosmolar non-ketogenic coma

  • This condition develops in diabetic patients as a result of osmotic dieresis caused by severe hyperglycemia, which leads to hyponatraemia and hypovolaemic shock.
  • The effect of the dehydration is most marked on the central nervous system. 

 Prolonged hyperglycemia can cause capillary basement membrane thickening, resulting in luminal narrowing.

Depending on the vessels involved, this could manifest as:

  • Diabetes nephropathy if the glomerular vessel basement membranes are involved.
  • Diabetic retinopathy occurs when the retina’s basement membrane is affected. Bleeding into the vitreous may occur, and as the haematoma organises, the fibrous tissue that forms contracts. This is known as retinitis proliferans, and it causes retinal detachment and cataract formation.
  • Microangiopathy causes ischaemic changes in the peripheral nerves, resulting in diabetes-related peripheral neuropathy. As a result, the hand and feet lose sensation symmetrically.



Glucose and Its Role in the Body

  • Glucose is a type of sugar found in the circulation that enters cells/tissues with the help of a hormone called insulin.
  • Sugar is one of the most important sources of energy for the body’s various activities.
  • Animals, including humans, typically obtain sugar from plants in the form of complex carbohydrates (starch).
  • These complex polysaccharides are broken down in the digestive system into simple sugars, which are then absorbed from the gut into the circulation and eventually become available to different cells/tissues of the body for energy production.
  • In the cells, these simple sugars are oxidized to produce the necessary energy in the form of adenosine triphosphate and adenosine diphosphate (ATP & ADP), a process known as oxidative phosphorylation.
  • Cell respiration refers to the process of metabolizing glucose in cells in the presence of oxygen to release energy required by the body for various physical activities. It occurs in the mitochondrion.

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