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Ari Eckman, M.D. and Sherita Golden, M.D., M.H.S.
02-03-2011
- Blood glucose level < 70 mg/dL (3.9 mmol/L)
- Clinically, hypoglycemia is suggested by typical symptoms (tremulousness, diaphoresis, tachycardia or mental status change) that is corrected by carbohydrate intake.
- Most often, hypoglycemia is caused by too much insulin or oral hypoglycemic agent, or not enough food intake.
- In patients receiving intensive therapy, risk of severe hypoglycemia is increased more than threefold.
- Average patient with type I diabetes suffers two episodes of symptomatic hypoglycemia per week and one episode of temporarily disabling hypoglycemia per year.
- In the Diabetes Control and Complications Trial (DCCT), more patients in intensively treated group had at least one episode of severe hypoglycemia (65 versus 35 percent in the control group), with overall rates of 61 and 19 per 100 patient-years, respectively.
- Risk factors: 1) type 1 diabetes which has not only insulin deficiency but usually deficient glucagon response; 2) history of hypoglycemia, hypoglycemia unawareness, or both; 3) aggressive glycemic therapy with lower glycemic goals; 4) recent moderate or intensive exercise; 5) irregular dietary intake; 6) sleep; and 7) renal failure
- See module on Nocturnal Hypoglycemia
- Documented by Whipple's triad: symptoms consistent with hypoglycemia, a low plasma glucose concentration, and relief of symptoms when plasma glucose concentration raised.
- American Diabetes Association Workgroup on Hypoglycemia classification of hypoglycemia in diabetes:
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Severe hypoglycemia: Requires assistance of another person to administer carbohydrate, glucagon, or other resuscitative actions. May develop sufficient neuroglycopenia to induce seizure or coma.
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Documented symptomatic hypoglycemia: Typical symptoms of hypoglycemia accompanied by a measured plasma glucose (PG) concentration < 70 mg/dl (3.9 mmol/l).
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Asymptomatic hypoglycemia: No symptoms of hypoglycemia but with a measured PG < 70 mg/dl (3.9 mmol/l).
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Probable symptomatic hypoglycemia: Symptoms of hypoglycemia not accompanied by a plasma glucose determination (but presumably caused by a PG < 70 mg/dl [3.9 mmol/l]). Treating symptoms suggestive of hypoglycemia with oral carbohydrate without a test of plasma glucose.
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Relative hypoglycemia: Typical symptoms of hypoglycemia, interpreted as hypoglycemia, but with measured PG >70 mg/dl (3.9 mmol/l). Patients with chronically poor glycemic control can experience symptoms of hypoglycemia at PG levels >70 mg/dl (3.9 mmol/l) as PG concentrations decline toward that level. Probably poses no direct harm.
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Hypoglycemia unawareness: Reduced sympathoadrenal and symptomatic response to low PG as a result of recurrent hypoglycemia
- Can be nonspecific
- As glucose levels fall, autonomic (adrenergic) symptoms occur initially, followed by neuroglycopenic symptoms (mental status changes) as glucose values decline further.
- Adrenergic (autonomic) symptoms: palpitations, anxiety, tremor, hunger, sensation of warmth, nausea and sweating
- Neuroglycopenic symptoms: fatigue, dizziness, headache, visual disturbances, drowsiness, difficulty speaking, inability to concentrate, abnormal behavior, loss of memory, difficulty thinking, and/or frank confusion, seizure, coma, and even death.
- Signs: diaphoresis and pallor are common; tachycardia, and systolic blood pressures mildly raised, and neuroglycopenic manifestations often observable.
- Occasionally, transient neurological deficits occur. Permanent neurological damage rare.
- If patient has hypoglycemia unawareness, may be asymptomatic.
- Prevention of hypoglycemia preferable to its treatment (Cryer)
- Patient's close friends or relatives should be aware of prevention strategies.
- Aggressive therapy, including 1) patient education 2) frequent self-monitoring blood glucose (SMBG), 3) flexible insulin and other drug regimens, 4) individualized glycemic goals, and 5) ongoing professional guidance and support
- Consider both conventional risk factors and those indicative of compromised glucose counterregulation.
- Review SMBG record to estimate frequency of hypoglycemia and adequacy of counterregulation, particularly before starting intensive insulin therapy or if there is previous history of hypoglycemic episodes.
- Consider less aggressive goals for A1c values in patients with severe hypoglycemia or with significant impairment in recovery from hypoglycemia, particularly in those with hypoglycemia unawareness.
- Continually reevaluate with patient the benefits of improved blood glucose control balanced against the risks of hypoglycemia.
- Medic-alert bracelet to facilitate rapid treatment in emergency settings
- Hypoglycemia is the limiting factor in reducing A1c too aggressively.
- Patients should have fast-acting carbohydrate (glucose tablets, hard candy, glucose paste, or sweetened fruit juice) available at all times.
- Self monitored blood glucose <70 mg/dL (3.9 mmol/L): reasonable to self treat (eat a glucose tablet or carbohydrate-containing juice, soft drinks, milk, candy, other snacks, or a meal).
- Recommended dose of glucose in adults is 20 grams (6 oz cup of orange juice or coca cola or 4 oz cup of grape juice).
- Clinical improvement should occur in 15-20 minutes.
- Since glycemic response to oral glucose lasts only about 2 hours, a more substantial snack or a meal should be taken shortly after initial treatment.
- Patients should be advised to monitor blood glucose levels serially after self-treating an episode of hypoglycemia to determine individual response to carbohydrate ingested.
- Friends and family should know never to put anything in the mouth of a person who is not able to sit up and ingest the food or drink. No cake paste, sugar, etc. in an unresponsive person.
- Train friends or relatives to recognize and treat hypoglycemia.
- If patient cannot eat or drink safely, use injectable glucagon.
- Glucagon: Subcutaneous or intramuscular injection of 0.5 to 1.0 mg used to treat patient who is unable to eat/drink. Usually recovery of consciousness within 10 to 15 minutes; may cause marked nausea and hyperglycemia 60 to 90 minutes later. Only one dose of glucagon should be administered within a 24-hour period.
- Check glucagon kit regularly; replace when beyond its expiration date.
- In medical setting (emergency department, office, hospital), 25 cc of 50 percent glucose (dextrose) intravenously will have immediate response.
- Subsequent glucose infusion (or food, if patient is able to eat) often needed, depending upon the cause of hypoglycemia
- Food should be provided orally as soon as patient able to ingest it safely.
- Hospitalization for prolonged treatment and observation may be necessary.
- In patients with clinical hypoglycemia unawareness, a 2- to 3-week period of diligent avoidance of hypoglycemia advisable to allow return of awareness of hypoglycemia(Cryer)
- Establish somewhat higher glucose targets in the short term
- More frequent self-monitoring of blood glucose, especially before driving or other dangerous activities.
- With severe hypoglycemia, particularly at night or with unawareness, consider continuous glucose monitoring.
- Hypoglycemia establishes the lower limit of blood glucose control. It is unpleasant, potentially dangerous and can (rarely) be fatal.
- Minimize the frequency and severity of hypoglycemia, avoiding especially nocturnal hypoglycemia.
- Replace insulin in a physiologic fashion to compensate for compromised glucose counterregulation.
- To avoid overcorrection of hypoglycemia, with rebound hyperglycemia, wait 15-20 minutes before further treatment.
- A low A1c (i.e. 5.5%) may indicate unrecognized hypoglycemic events, especially between meals or overnight, and may indicate need for closer monitoring.
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