The effects of extremely high blood sugar can have short-term effects on the body and can also cause permanent health problems. High blood sugar levels most often occur from the effects of unrecognized diabetes. Normal, fasting blood sugar level values range from 70 to 99 mg/dl, according to Mission Health System. Blood sugar levels in those who are fasting that are above 126 mg/dl may indicate illness. Higher than normal results in a fasting state may signal diabetes, an overactive thyroid, pancreatitis or pancreatic cancer.
HHNS
Extremely high blood sugar levels lead to a condition known as Hyperosmolar Hyperglycemic Nonketotic Syndrome (HHNS). This leads to excessive urine output, as the body attempts to get rid of sugar. Uncontrolled type 2 diabetes is a common reason for dehydration from HHNS. Stress, steroid medications, vomiting, diarrhea and sudden serious illness can lead to dehydration and extremely high blood sugar levels. Seizures and coma can follow.
Ketoacidosis
Extremely high blood sugar levels can lead to a condition known as diabetic ketoacidosis (DKA), which occurs when the body is depleted of insulin and begins to burn fat for energy. The result is increased ketone levels in the body that are also toxic. Undiagnosed type 1 or type 2 diabetes is often the culprit for ketoacidosis from extremely high blood sugar levels. Individuals with known diabetes can experience high ketone levels from illnesses, such as infection, stroke, heart attack and trauma. Ketones can be measured in the urine using a dipstick that changes color to indicate their presence, as well as signal diabetic ketoacidosis. Symptoms are dry mouth, thirst, frequent urination and a very high serum blood sugar level. Vomiting, confusion and coma indicate worsening ketoacidosis.
Sudden Cardiac Death
Children with extremely high blood sugar levels who develop diabetic ketoacidosis could be at risk for sudden cardiac death. A study by Jill M. Baren, MD, published in the July 25, 2008 edition of "Journal Watch Emergency Medicine," titled "Effect of DKA on QTc Prolongation in Children Might Be Mediated by Ketosis, Not Electrolyte Abnormalities," found that high blood sugar levels could predispose one to life-threatening heart rhythm disturbance and death.
Kidney Failure
A series of events related to extremely high blood sugar can also lead to kidney failure. Dehydration from HHNS or diabetic ketoacidosis depletes the body of fluid volume (hypovolemia), placing stress on the kidney. The low blood pressure that results from hypovolemia, in turn, reduces blood flow to the kidney, causing acute damage. Disturbances in electrolytes (potassium, sodium, bicarbonate and carbon dioxide) also result in kidney dysfunction that can lead to failure.
Cerebral Edema
Brain swelling, called cerebral edema, can be a serious complication of extremely high blood sugar levels that can lead to death. Pediatric patients are especially vulnerable. The exact cause is not known. Dehydration causes fluid shifts between circulating and cell volume. Treatment for extremely high blood sugar levels is thought to cause fluids to reverse back into cells and cause cerebral edema, especially if hydration and lowering of blood sugar levels occurs too rapidly. Cerebral edema that can occur from diabetic ketoacidosis is addressed for clinicians in the February 2005 "Neurocritical Care" journal, in the "Cerebral Edema During Treatment of Diabetic Ketoacidosis in an Adult With New Onset Diabetes" article by Patrick J. Troy, et al.
