Type 1 Diabetes and Hypoglycemia

Woman experiencing hypoglycemia
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This weekend, I was called by a physician at New York Presbyterian Hospital after a patient of my colleague’s was brought to the emergency room for a hypoglycemic seizure. The patient in question is a young man with type 1 diabetes with frequent hospitalizations for hypoglycemia despite careful blood glucose monitoring and meticulous insulin management. In fact, one week prior, the patient experienced a seizure on the subway and hit his face on the train floor after his sugars dropped in the 20s.

After adjusting the amount of insulin he is receiving through his pump, I sat down to write this blog.

Patients ask me all the time, “what is the definition of hypoglycemia.” I’m always at a bit of a loss since hypoglycemia is a bit of a vague term and refers to abnormally low blood glucose levels with or without symptoms which potentially expose the individual to harm. Patients with diabetes should suspect hypoglycemia when blood glucose levels are ≤70mg/dl.  However, this cutoff value is controversial, with some doctors arguing that a value of < 63mg/dl is more appropriate. The value of 70 was chosen because this was the highest blood glucose value at which the body can produce a “ fight or flight” reaction.

Symptoms of hypoglycemia include sweating, tremors, palpitations, hunger and anxiety. More severe symptoms include decreased concentration, confusion, blurry vision, lethargy, seizures, and comas.

Hypoglycemia is subdivided into five categories:

  • Severe hypoglycemia- this is the case when the assistance of others is required in the form of glucagon or other resuscitation.
  • Documented symptomatic hypoglycemia- the patient has symptoms typically associated with hypoglycemia and a documented blood sugar level of ≤70mg/dl. 
  • Asymptomatic hypoglycemia- the patient doesn’t have any symptoms but blood sugar levels are ≤70mg/dl.
  • Probable symptomatic hypoglycemia- Patient has typical symptoms of hypoglycemia but blood glucose levels aren’t documented
  • Pseudohypoglycemia- Patient has typical symptoms of hypoglycemia but blood glucose levels are ≥70mg/dl. This reflects chronically poor glucose control. For example, a patient who lives with blood glucose levels in the 300s will often develop tremors and palpitations when blood glucose levels drop to the mid 150s.

The average patient with type 1 diabetes experiences two episodes of symptomatic hypoglycemia per week and one episode of severe hypoglycemia per year.  It is difficult to say exactly how hypoglycemia affects long-term prognosis. In one study, hypoglycemia was found to cause 4-10% of deaths of patients with type 1 diabetes. It is also unclear how recurrent hypoglycemia affects cognition. In one large study, there were no significant long-term neurological changes in patients with repeated episodes of hypoglycemia. We do know that elderly patients have more marked responses to hypoglycemia with more rapid development of dizziness, delirium, and weakness.

The most common cause of hypoglycemia in patients with type 1 diabetes is clearly insulin use.

Some patients with type 1 diabetes may also be using Glucagon-Like Peptide 1 agents (for example, Byetta and Victoza) as well Sodium-Glucose Co-transporter 2 Inhibitors (for example, Jardiance and Invokana). These medications should not cause hypoglycemia on their own. However, when co-administered with insulin, they increase the risk of hypoglycemia.

Insulin excess, however, cannot fully explain the frequency and severity of hypoglycemic episodes in type 1 diabetes. The loss of hormones which counteract hypoglycemia is likely jointly responsible. The pancreatic hormone, glucagon, which raises low blood sugars, is lost along with insulin in patients with type 1 diabetes.

In addition, adrenaline, which also fights low blood glucose levels, is often inadequate.

There are various strategies for preventing hypoglycemia (do not attempt any of these strategies on your own; consult with your doctor first):

  • Target blood glucose levels should be adjusted in patients with recurrent episodes of hypoglycemia or in elderly patients who may have more severe reactions to hypoglycemia.  It may be appropriate to allow blood glucose levels to rise to prevent life- threatening hypoglycemic episodes despite the long-term risk of complications such as cardiovascular disease. This can be achieved by cutting back insulin doses.
  • In addition, long-acting insulin analogs such as glargine and detemir along with rapid-acting bolus insulin analogs such as lispro and aspart are less likely to cause hypoglycemia than regular or NPH insulin.
  • Patients with frequent hypoglycemia episodes may develop a phenomenon known as “hypoglycemic unawareness”. Generally, this can be reversed by having a 2-3 week period with no hypoglycemia. 
  • Sensor-augmented pumps which slow down or stop the infusion of insulin for up to two hours when the sensor detects hypoglycemia have been proven to decrease the incidence of nighttime hypoglycemia.

The treatment of hypoglycemia depends on the severity:

  • When patients are asymptomatic with blood glucose levels ≤70mg/dl, watchful waiting rather than immediate treatment may be appropriate to avoid rebound hyperglycemia. Options include serial blood glucose testing to check for resolution or increased carbohydrate intake.
  • When patients are moderately symptomatic, fast-acting carbohydrates such as glucose tablets or fruit juice should be used to raise sugars quickly. In general, 15-20 grams should suffice. A long-acting carbohydrate is also advisable to prevent recurrent hypoglycemia.
  • If a patient is unconscious, the most effective at-home treatment is glucagon. Generally, an injection of 0.5 to 1mg of glucagon will allow patient to regain consciousness within 10-15 minutes.  Once in the ER, patients generally receive intravenous glucose infusions.

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