DM: Hypoglycemia Flashcards
What is the Whipple’s triad?
- Symptoms consistent with hypoglycemia
- Low plasma glucose concentration measured with a precise method
- Relief of symptoms the after plasma glucose level is raised
Lower limit of fasting plasma glucose concentration
~70 mg/dL
Duration of fasting in which hepatic glycogen stores are usually sufficient to maintain plasma glucose levels
~8 hours
What is the first defense against hypogclyemia?
Decrease in insulin secretion (primary glucose regulatory factor)
What are the primary counterregulatory hormones?
Glucagon and epinephrine
True or False: Cortisol and growth hormone play a role in the defense against acute hypoglycemia.
False. They are able to support glucose production and restrict glucose utilization to a limited amount (~20% compared to epinephrine).
What is the second defense against hypoglycemia?
Increased glucagon
What is the third defense against hypoglycemia?
Increased epinephrine
Hypoglycemia unawareness is reversible by as little as _____ weeks of scrupulous avoidance of hypoglycemia in most affected patients.
2-3 weeks
How does alcohol intake cause hypoglycemia?
Alcohol blocks gluconeogenesis
How does sepsis cause hypoglycemia?
Increased glucose utilization is induced by cytokine production in macrophage-rich tissues such as the liver, spleen, and lung.
TRUE OR FALSE: Cortisol and growth hormone are critical in the prevention of hypoglycemia.
False
What is the mechanism of hypoglycemia in patients with non-beta-cell tumors?
Overproduction of an incompletely processed form of insulin-like growth factor II (“big IGF-II”)
What is the mechanism of hypoglycemia in patients with primary beta cell disorder or with intake of insulin secretagogue?
Failure of insulin secretion to fall to very low levels during hypoglceymia
Critical diagnostic findings in endogenous hyperinsulinism
Plasma insulin >=3 uU/mL
Plasma C-peptide >=0.6 ng/mL
Plasma proinsulin >=5 pmol/L
-When plasma glucose <55 mg/dL + symptoms of hypogclyemia
(Insulin, C-peptide, and proinsulin levels are inappropriately high in the setting of a low plasma glucose concentration)
What indicates increased insulin (or IGF) action after IV administration of glucagon? (level of B-hydroxybutyrate and glucose)
Low plasma beta-hydroxybutyrate concentration and an increment in plasma glucose level
What is nesidioblastosis?
It refers to diffuse islet involvement with beta cell hypertrophy, and sometimes hyperplasia, which leads to fasting endogenous hyperinsulinemic hypoglycemia
What is the term used to denote patients with diffuse beta cell hypertrophy and develops postprandial hypoglycemia?
Noninsulinoma pancreatogenous hypoglycemia
Which drugs can be given to treat hypoglycemia in patients with inoperable insulinomas?
Diazoxide (potassium channel activator that inhibits insulin secretion)
Octreotide (somatostatin analogue)
Everolimus (mammalian target of rapamycin inhibitor)
What causes pseudohypoglycemia?
Continued glucose metabolism by the formed elements of the blood ex vivo, particularly in the presence of leukocytosis, erythrocytosis, or thrombocytosis, or with delayed separation of the serum from the formed elements
Which inborn errors of metabolism cause fasting hypoglycemia?
1) disorders of glycogenolysis:
glycogen storage disease
types 0
I - high lactate before meals, high triglycerides
III - low lactate after meals, high triglycerides, high ketones
IV
Fanconi-Bickel syndrome
2) defects in fatty acid oxidation (carnitine cycle, fatty acid beta oxidation, electron transfer, ketogenesis)
3) defects in gluconeogenesis (fructose-1, 6-bisphosphatase)
Which inborn errors of metabolism cause postprandial hypoglycemia?
1) glucokinase, SUR1, and Kir6.2 potassium channel mutations
2) congenital disorders of glycosylation
3) inherited fructose intolerance
Which inborn errors of metabolism cause exercise-induced hypoglycemia?
Increased activity of monocarboxylate transporter 1 in beta cells which causes hyperinsulinemia
What is the reasonable initial dose of glucose in a person with acute hypoglycemia?
15-20 g of glucose
