Understanding Hypoglycemia

 

Anyone who takes insulin or other glucose-lowering medications, either alone or in combination with other antidiabetic drugs, is prone to hypoglycemia. Hypoglycemia, or low blood sugar, is less common among people with type 2 diabetes than among those with type 1, but it can be serious when it occurs. Blood sugar may fall abnormally low from too much insulin, too much exercise, too little food or carbohydrates, a missed or delayed meal, or a combination of these factors. As you pursue near-normal blood sugar control more aggressively, your risk for hypoglycemia increases. It’s important that people with diabetes, and those who live and work with them, learn to recognize and understand hypoglycemia so it can be prevented and treated before it becomes a life-threatening crisis.

 

 

Symptoms of Hypoglycemia

• nervousness
• weakness
• hunger
• lightheadedness or dizziness
• trembling
• sweating
• rapid heartbeat
• feeling cold and clammy
• irritability
• confusion
• drowsiness
• slurred speech
• double vision
• in severe cases, loss of consciousness, seizures, and even coma

Hypoglycemia can produce a variety of symptoms and effects, but the principal problems arise from an inadequate supply of glucose as fuel to the brain, resulting in impairment of function (neuroglycopenia). Effects can range from vaguely "feeling bad" to coma and (rarely) permanent brain damage or death.

For patients with diabetes, hypoglycemia often occurs when a treatment to lower the elevated blood glucose of diabetes "overshoots" and causes the glucose to fall to a below-normal level.

From a strictly scientific standpoint, however, this is an oversimplification of what actually occurs in the body. Iatogenic hypoglycemia is typically the result of the interplay of absolute or relative insulin excess and compromised glucose counterregulation in type 1 and advanced type 2 diabetes. Decrements in insulin, increments in glucagon, and, absent the latter, increments in epinephrine stand high in the hierarchy of redundant glucose counterregulatory factors that normally prevent or rapidly correct hypoglycemia. In insulin-deficient diabetes (exogenous) insulin levels do not decrease as glucose levels fall, and the combination of deficient glucagon and epinephrine responses causes defective glucose counterregulation.

Furthermore, reduced sympathoadrenal responses can cause hypoglycemia unawareness. The concept of hypoglycemia-associated autonomic failure (HAAF) in diabetes posits that recent incidents of hypoglycemia causes both defective glucose counterregulation and hypoglycemia unawareness. By shifting glycemic thresholds for the sympathoadrenal (including epinephrine) and the resulting neurogenic responses to lower plasma glucose concentrations, antecedent hypoglycemia leads to a vicious cycle of recurrent hypoglycemia and further impairment of glucose counterregulation. In many cases (but not all), short-term avoidance of hypoglycemia reverses hypoglycemia unawareness in most affected patients.