What is hyperglycemia?

The presence of abnormally high levels of sugar (glucose) in the blood is known as hyperglycemia. Blood normally contains 70 to 100mg/dL of glucose after fasting for 8 hours and never rises above 180mg/dL two hours after a meal (post-prandial). In hyperglycemia, fasting glucose levels can be as high as 130mg/dL which may shoot up to 200mg/dL post-prandial. Hyperglycemia is the most prominent feature of diabetes mellitus. Non-diabetics may also experience hyperglycemia after a severe injury, major surgery or emotional stress.

What are the symptoms?

The symptoms of hyperglycemia are similar to that of diabetes mellitus and include:

  • Polyuria (frequent urination)
  • Polydipsia (frequent thirst)
  • Polyphagia (feeling hungry too often)
  • Blurred vision
  • Headache
  • Fatigue
  • Dry skin and mouth

Chronic hyperglycemia causes functional impairment of multiple organs in the body, which may manifest as :

  • Diabetic ketoacidosis (primarily in type I diabetes)
    – Ketonuria (presence of ketones in urine)
    – Fruity odor in the breath
  • Diabetic coma (usually in type II diabetes)
  • Cardiovascular disease
  • Diabetic retinopathy (damage to blood vessels of the retina)
  • Diabetic nephropathy (damage to kidneys)
  • Diabetic neuropathy (nerve damage)
  • Teeth and gum infections
  • Osteoporosis
  • Wounds that heal slowly
  • Higher susceptibility to skin infections
  • Erectile dysfunction

What causes hyperglycemia?

Glucose, the primary fuel for the body, enters the blood through digested food, mobilization from glycogen reserves or gluconeogenesis (glucose synthesis from non-carbohydrate sources). It is cleared from the blood by cellular uptake, storage as glycogen in liver and muscle and excretion via kidneys. The hormone, insulin regulates glucose uptake by cells. Hyperglycemia occurs when more glucose is added as compared to the amount being cleared from blood. Therefore, blood glucose levels elevate when there is :

  • High dietary intake of carbohydrates and fats without enough physical activity.
  • Insulin insufficiency which impairs the entry of glucose into cells, as in Type I diabetes as well as autoimmune reactions against pancreas.
  • Insulin resistance, common in Type II and gestational diabetes where cells fail to take up blood glucose, in spite of sufficient insulin in circulation.
  • Impaired glucose storage in liver due to chronic liver disease.
  • Kidney malfunction and poor excretion of the excess sugar.
  • Stress (injury, infection, surgery, emotional) which causes release of hormones (adrenaline, cortisol) which trigger hyperglycemia.
  • Treatment with steroid medications.

Persistently elevated blood glucose levels are a sign of diabetes mellitus. While the odd episode may arise due to other causes above, it either resolves are removal of the cause or is temporary. In diabetes mellitus, hyperglycemia is persistent because the condition is incurable although it can be managed over the long term.

How is hyperglycemia treated?

Acute hyperglycemia is controlled by administering shots of rapid-acting insulin along with fluid and electrolyte replacement. The treatment of chronic hyperglycemia involves controlling the blood sugar levels by a combination of :

  • Insulin therapy
  • Medications that lower blood sugar either by lowering glucose production in liver (metformin) or stimulate the pancreas to secrete more insulin (glipizide) or increase the sensitivity of body tissues to insulin (plioglitazone). Antibiotics may be given if a microbial infection has caused hyperglycemia.
  • Appropriate dietary plan.
  • Adequate exercise, except in cases of diabetic ketoacidosis where exercise further elevates blood glucose

This should be augmented with regular tests of blood glucose and appropriate modification of the treatment regime.

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