Insulin resistance in Cushing's syndrome.
Level 4 - case-series / case-control
Small cross-sectional physiological comparison across clinical groups
PubMed 3905556 · doi:10.1055/s-2007-1013593
What was done
Researchers performed euglycemic insulin clamps across three groups: 4 patients with Cushing's syndrome, 5 obese individuals, and 5 normal volunteers. Insulin was infused at 0.3, 1, 3, and 10 mU/kg/min to assess glucose disposal rates and maximal insulin clearance.
What was found
Glucose disposal at maximal insulin levels was 11.9 +/- 0.4 mg/kg/min in normal controls, decreased by 29% in obese patients, and decreased by 42% in Cushing's syndrome patients. Half-maximally effective insulin concentrations were increased in both patient groups compared to controls. Maximal insulin clearance rates were 1460 +/- 200 ml/min/m2 in normal controls, not significantly changed in obese patients, and decreased by 40% in Cushing's syndrome patients.
Why it matters
The findings show that insulin resistance in hypercorticism is physiologically distinct from simple obesity, driven by both decreased maximal insulin responsiveness and impaired insulin clearance.
Limits
The study has an extremely small sample size (N = 14 total; 4 Cushing's, 5 obese, 5 controls). The abstract does not provide exact p-values, confidence intervals, or details on age, sex, and baseline characteristics.
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