A 19-year-old man comes to the office due to frequent episodes of disorientation, palpitations, tremulousness, and excessive sweating over the past 3 months. He says the symptoms resolve quickly after drinking some juice or a carbonated beverage. The patient was diagnosed with type 1 diabetes mellitus at age 12 and takes short- and long-acting insulin. He has had no dose changes in the past 2 years or diabetic complications and follows up with an ophthalmologist frequently. The patient is a college student and reports some stress due to an upcoming midterm examination. He does not use tobacco, alcohol, or illicit drugs. Vital signs and physical examination are within normal limits. Laboratory results show a hemoglobin A1c of 6.8% and no proteinuria. Which of the following factors most likely precipitated this patient's current symptoms?

Question

A 19-year-old man comes to the office due to frequent episodes of disorientation, palpitations, tremulousness, and excessive sweating over the past 3 months.  He says the symptoms resolve quickly after drinking some juice or a carbonated beverage.  The patient was diagnosed with type 1 diabetes mellitus at age 12 and takes short- and long-acting insulin.  He has had no dose changes in the past 2 years or diabetic complications and follows up with an ophthalmologist frequently.  The patient is a college student and reports some stress due to an upcoming midterm examination.  He does not use tobacco, alcohol, or illicit drugs.  Vital signs and physical examination are within normal limits.  Laboratory results show a hemoglobin A1c of 6.8% and no proteinuria.  Which of the following factors most likely precipitated this patient's current symptoms?

Quizplus · Accepted Answer

11ec160b_3cb0_9799_9249_435202736f7b_MD0001_00 This patient has frequent symptomatic hypoglycemia-disorientation, sweating, and palpitations, which are relieved by intake of glucose-despite no changes to his chronic insulin regimen. Hypoglycemia is often induced in patients with type 1 diabetes by inadvertent overdose of insulin or decreased carbohydrate intake (eg, skipped meal), but can also be triggered by intensive physical activity/exercise. Glucose uptake by skeletal muscle cells is mediated by glucose transporter type 4 (GLUT4). GLUT4 is translocated to cell membranes and transverse tubules (deep invaginations in the cell membrane) in response to insulin. GLUT4 translocation also occurs during muscle contraction by an insulin-independent mechanism, which is mediated by several cellular factors, including AMP-activated kinase, nitric oxide, and calcium-calmodulin-activated protein kinase. In normal individuals, overt hypoglycemia does not occur with exercise because a drop in blood glucose suppresses insulin release from the beta cells, and counterregulatory hormones (eg, glucagon) increase endogenous glucose production via glycogenolysis and gluconeogenesis. However, patients taking exogenous insulin are vulnerable to exercise-induced hypoglycemia because insulin will continue to be released from the injection site despite falling glucose levels. (Choice A) Patients with hereditary fructose intolerance cannot break down fructose and develop hypoglycemia and vomiting after ingestion of fructose-containing foods. However, this typically presents at the age of weaning (when fructose is introduced) and patients often develop a protective distaste for sweets. Ingestion of fructose-containing juice and soda would worsen the hypoglycemia, not correct it. (Choices C, D, and E) Infection, pain, sleep deprivation, and severe mental/emotional distress tend to cause hyper- rather than hypoglycemia due to increased production of counterregulatory hormones (eg, catecholamines, cortisol). These hormones raise glucose by increasing glycogenolysis and gluconeogenesis and decreasing pancreatic insulin secretion (in patients with residual islet cell function). (Choice F) Weight gain is associated with insulin resistance. Insulin-treated patients who gain weight usually develop hyperglycemia and require increased doses of insulin to maintain control of glucose. Educational objective: Uptake of glucose by skeletal muscle is mediated by the glucose transporter type 4, which is translocated to the cell membrane in response to insulin and muscle contraction. Hypoglycemia can be precipitated by exercise in patients with insulin-treated diabetes due to the persistent effects of exogenous insulin. __________ References: Exercise, GLUT4, and skeletal muscle glucose uptake. (http://www.ncbi.nlm.nih.gov/pubmed/23899560)

A 19-Year-Old Man Comes to the Office Due to Frequent