Description

• Abnormally low concentration of glucose in circulating blood of diabetic; often referred to as an insulin reaction
• Classification includes:
  • Severe hypoglycemia: An event requiring assistance of another person to actively administer treatment
  • Documented symptomatic hypoglycemia: An event during which typical symptoms are accompanied by a measured plasma glucose of ≤70 mg/dL (3.9 mmol/L)
  • Asymptomatic hypoglycemia: An event not accompanied by symptoms, but a measured glucose of ≤70 mg/dL (3.9 mmol/L)
  • Probable symptomatic hypoglycemia: Event with symptoms, but glucose not tested
  • Relative hypoglycemia: An event with typical symptoms, but glucose >70 mg/dL (3.9 mmol/L)
• Hypoglycemia is the leading limiting factor in the glycemic management of type 1 and type 2 diabetes. Severe or frequent hypoglycemia requires modification of treatment regiments, including higher treatment goals (1).
• System(s) affected: Endocrine/Metabolic

• Major risk factor for severe hypoglycemic reactions
• Most commonly found in patients with long-standing type 1 diabetes and children <7 years

Epidemiology

Incidence From the Accord Study, the annual incidence of hypoglycemia was:

• 3.14% in the intensive treatment group
• 1.03% in the standard group
• Increased risk among women, African Americans, those with less than a high school education, aged participants, and those who used insulin at trial entry
• From the RECAP-DM study: Hypoglycemia was reported in 38% of type 2 patients who added a sulphonylurea or a thiazolinedione to metformin therapy during the past year.

Risk Factors

• Nearly 3/4 of severe hypoglycemic episodes occur during sleep.
• Autonomic neuropathy
• Illness, stress, and unplanned life events
• Duration of diabetes >5 years, advanced age, renal/liver disease, CHF, hypothyroidism, hypoadrenalism, gastroenteritis, gastroparesis (unpredictable CHO delivery)
• Starvation or prolonged fasting
• Alcoholism: Evening consumption of alcohol is associated with an increased risk of nocturnal and fasting hypoglycemia, especially in type 1 patients.
• Current smokers with type 1 diabetes
• Oral hypoglycemics with long duration and high potency have greater hypoglycemic risks.
• Insulin secretagogues: Sulfonylureas (Glipizide, Glibenclamide, Glibornuride, Gliclazide, Chlorpropamide, Glimepiride); glinide derivatives (Repaglinide, Nateglinide) stimulate insulin secretion and can cause hypoglycemia. Hypoglycemia is rare in diabetics not treated with insulin or insulin secretagogues (1).
• In patients 80 years or older, severe hypoglycemia is associated with comorbid conditions and in users of a long-acting sulphonylurea.
• Intensive insulin therapy (further lowering A1C from 7% to 6%) is associated with higher rate of hypoglycemia (2).

General Prevention

• Maintain routine schedule of diet, medication, and exercise.
• Stabilize daily carbohydrate intake.
• Regular blood glucose testing if taking insulin or insulin secretagogue:
  • ≥3 times daily testing if multiple injections of insulin, insulin pump therapy, or pregnant diabetic; frequency and timing dictated by needs and treatment goals
  • Particularly helpful for asymptomatic hypoglycemia
• Diabetes treatment and teaching programs (DTTPs) especially for high-risk type 1 patients, which teach flexible insulin therapy to enable dietary freedom
• Use of rapid-acting and long-acting insulin analogs is associated with less hypoglycemia (3).
• Hypoglycemia rates are reduced by up to 70% using continuous SC insulin infusion pumps compared with multiple daily injections (4)[C].
• Continuous glucose monitoring may supplement self-glucose monitoring and is especially useful with hypoglycemic unawareness and/or frequent hypoglycemic episodes (1).
• If pre-exercise glucose is <100 mg/dL and taking insulin or secretagogue, then carbohydrate consumption or reduction in medication may prevent hypoglycemia.

Etiology

• Loss of hormonal counter-regulatory mechanism in glucose metabolism
• Diet: Too little food (skipping meal), decreased carbohydrate intake
• Medication: Too much insulin or oral hypoglycemic agent (improper dose or timing)
• Erratic absorption of insulin or oral hypoglycemics
• Adverse reaction from other medications
• Exercise/physical activity: Unplanned or excessive
• Alcohol consumption
• Vomiting or diarrhea
• Gastroparesis

Commonly Associated Conditions

• Autonomic dysfunction
• Neuropathies
• Cardiomyopathies
• Older type 2 diabetics with severe hypoglycemia have a higher risk of dementia (5).