• Vol. 43 No. 2, 113–119
  • 15 February 2014

Identification of Insulin Resistance in Subjects with Normal Glucose Tolerance



Introduction: Decreased insulin action (insulin resistance) is crucial in the pathogenesis of type 2 diabetes. Decreased insulin action can even be found in normoglycaemic patients, and they still bear increased risks for cardiovascular disease. In this study, we built models using data from metabolic syndrome (Mets) components and the oral glucose tolerance test (OGTT) to detect insulin resistance in subjects with normal glucose tolerance (NGT).

Materials and Methods: In total, 292 participants with NGT were enrolled. Both an insulin suppression test (IST) and a 75-g OGTT were administered. The steady-state plasma glucose (SSPG) level derived from the IST was the measurement of insulin action. Participants in the highest tertile were defined as insulin-resistant. Five models were built: (i) Model 0: body mass index (BMI); (ii) Model 1: BMI, systolic and diastolic blood pressure, triglyceride; (iii) Model 2: Model 1 + fasting plasma insulin (FPI); (iv) Model 3: Model 2 + plasma glucose level at 120 minutes of the OGTT; and (v) Model 4: Model 3 + plasma insulin level at 120 min of the OGTT.

Results: The area under the receiver operating characteristic curve (aROC curve) was observed to determine the predictive power of these models. BMI demonstrated the greatest aROC curve (71.6%) of Mets components. The aROC curves of Models 2, 3, and 4 were all substantially greater than that of BMI (77.1%, 80.1%, and 85.1%, respectively).

Conclusion: A prediction equation using Mets components and FPI can be used to predict insulin resistance in a Chinese population with NGT. Further research is required to test the utility of the equation in other populations and its prediction of cardiovascular disease or diabetes mellitus.

Currently, type 2 diabetes is a leading cause of death in Taiwan, as well as in many other countries. It places a tremendous burden not only on patients themselves but also on patients’ families and society. Although which process occurs first remains controversial, both insulin resistance and impaired insulin secretion are the 2 principal causes of type 2 diabetes. According to the Insulin Resistance Atherosclerosis Study, approximately 85.7% to 93.2% of type 2 diabetes patients have insulin resistance. In addition, Reaven et al5 found that approximately 30% of normoglycaemic patients can be classified as insulin-resistant. Insulin-resistant patients were proven to have a higher cardiovascular risk than those without. Therefore, it is crucial to identify insulin resistance in normoglycaemic patients. Preventive interventions, such as lifestyle modification, can be suggested to this apparently healthy cohort.

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