Section 10: Endocrinologic Disorders
Which of the following best describes the biochemical derangements and clinical features associated with type 1 diabetes mellitus?
A. Hyperinsulinemia, ketosis-prone, patients usually present with hypoglycemia
B. Insulin resistance, loss of phase 1 insulin release, most commonly develops in older adults
C. Low C-peptide concentrations, beta cell destruction, most commonly develops in adolescents
D. High postprandial GLP-1 levels, obesity, patients usually present with no or only mild symptoms
The answer is C. Type 1 diabetes is caused by an autoimmune process that destroys the beta-cells in the pancreas, resulting in an absolute insulin deficiency. C-peptide, created by the cleavage of proinsulin, is a marker of endogenous insulin production. Therefore, C-peptide serum concentrations are very low or zero in patients with type 1 diabetes. While type 1 diabetes can occur at any age, it most commonly develops in childhood with the peak incidence occurring in the early adolescent years prior to puberty (10-14 years old). See “Clinical Presentation” section.
All of the following are commonly observed in patients with type 2 diabetes mellitus EXCEPT:
A. Declining beta-cell mass
B. Reduced hepatic glucose output
C. Increased postprandial glucagon release
D. Diminished incretin hormone release following meals
The answer is B. Patients with type 2 diabetes have excessive hepatic glucose production which is driven by inappropriate glucagon release (Answer C) and diminished sensitivity to insulin in the liver. Patients with type 2 diabetes have declining beta-cell mass over time and typically have less than 50% of normal beta-cell mass at the time of diagnosis (Answer A). Diminished incretin normal release following meals (Answer D) is commonly seen in patients with type 2 diabetes. See “Pathophysiology” section.
Which of the following would meet the diagnostic criteria for diabetes mellitus?
A. A fasting plasma glucose of 119 mg/dL (6.6 mmol/L)
B. A hemoglobin A1C value of 6.6% (0.066; 49 mmol/mol Hb)
C. A plasma glucose of 181 mg/dL (10.0 mmol/L) at 2 hours during a 75-g oral glucose tolerance test (OGTT)
D. A random plasma glucose of 192 mg/dL (10.7 mmol/L) after a meal; the patient reports no symptoms and gained 5 lb (2.3 kg) over the last 6 months
The answer is B. The diagnosis of diabetes mellitus is based on evidence ...