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Insulin sensitivity in cardiological syndrome X
A Quiønones Galvan1, A Natali, E Muscelli
1Metabolism Unit, National Research Council (CNR), Institute of Clinical Physiology, Pisa, Italy.
Journal of Internal Medicine
|March 1, 1996
Summary
Cardiological syndrome X is not an insulin-resistant state. Studies show normal insulin sensitivity and substrate oxidation in patients with this condition, suggesting secondary causes for any observed insulin resistance.
Area of Science:
- Cardiology
- Metabolic Research
- Endocrinology
Background:
- Cardiological Syndrome X, characterized by angina despite normal coronary arteries, has been hypothesized to be linked to insulin resistance.
- Previous studies have yielded conflicting results regarding insulin sensitivity in patients with Syndrome X.
Purpose of the Study:
- To investigate whether patients diagnosed with 'pure' Syndrome X exhibit impaired insulin sensitivity.
- To assess insulin's in vivo actions, including glucose disposal and substrate oxidation, in this patient group.
Main Methods:
- A case-control study comparing 10 patients with Syndrome X to 13 matched healthy controls.
- Insulin sensitivity and substrate oxidation were evaluated using the euglycaemic insulin clamp technique combined with indirect calorimetry.
Main Results:
- Patients with Syndrome X demonstrated normal fasting glucose and insulin levels compared to controls.
- Glucose disposal rates, non-oxidative glucose disposal, resting energy expenditure, and insulin-induced thermogenesis were similar between groups.
- Fasting plasma NEFA concentrations and insulin-induced hypokalaemia were also comparable in both patients and controls.
Conclusions:
- The study found no evidence of impaired in vivo insulin action in patients with Syndrome X.
- Cardiological Syndrome X is not inherently an insulin-resistant state; any observed insulin resistance is likely secondary to other factors.