Metabolic Syndrome, Diabetes, and Coronary Artery Disease: a Very Common Association

To the Editor,

We read with interest Jover et al's article¹ on the prevalence of metabolic syndrome (MS) in patients with acute coronary syndrome. The authors included a subanalysis of the components of MS after excluding 265 patients with known diabetes. The main characteristic of patients with MS is the presence of insulin resistance. An association between MS and abdominal obesity, atherogenic hyperlipidemia, inflammation, and increased risk of cardiovascular disease has also been reported.² Insulin resistance is also one of the most important pathogenic factors in the development of diabetes mellitus and atherosclerosis, two conditions with parallel natural histories from the rise in blood insulin and fatty material to clinical hyperglycemia and acute atherothrombotic events.³ We consider it important to highlight the relationship between MS, diabetes, and cardiovascular disease. We therefore provide new data from a recent analysis of the prevalence study of newly diagnosed diabetes in percutaneous coronary interventions (PCI) published by our group.⁴.

A total of 580 patients undergoing PCI were included in a prospective study. An oral glucose tolerance test (OGTT) was performed in 83% of nondiabetic patients to establish their glucometabolic status and screen for occult diabetes. Patients in whom an OGTT was performed had a mean age of 66.5 years; 80.1% were male, 49.7% had hypertension, 35.6% were obese, 37.3% had had a previous infarction, and 76% of patients received PCI for acute coronary syndrome.

After the OGTT, 41.4% of patients were considered normoglycemic and 22.8% had newly diagnosed diabetes (blood glucose at 2h>200mg/dl). In total, 198 patients (58.6%) had some alteration in carbohydrate metabolism and abnormal glucose regulation. Based on International Diabetes Federation (IDF) criteria, the prevalence of MS in the study population was 59.9%. This figure compares to one of 51.3% obtained using the Adult Treatment Panel III (ATPIII) criteria and a figure of 42.6% using World Health Organization (WHO) criteria. Of patients undergoing PCI, 28.4% met all 3 criteria for MS.

The prevalence of newly diagnosed diabetes was higher among patients with MS, regardless of the criteria used: IDF, 31% vs 13.3% (P<.001); WHO, 42.7% vs 13% (P<.001); ATPIII, 32.5% vs 14.5% (odds ratio [OR]=3.4, P<.001). A multivariate analysis to determine the independent association between MS and newly diagnosed diabetes gave the following results after adjusting for age, sex, and clinical and laboratory variables: IDF criteria, OR=3.3 (95% confidence interval [95%CI], 1.7 to 6.3, P<.001); WHO, OR=5.5 (95%CI, 3.1 to 9.9, P<.001); ATPIII OR=3.4 (95%CI, 1.9 to 6.1, P<.001). There was therefore a clear and strong relationship between newly diagnosed diabetes and MS, regardless of the diagnostic criteria used.

Data from this study reinforce those reported by Jover et al.,¹ which also indicated a high prevalence of MS in patients with coronary disease. They also provide further evidence of the strong relationship between MS and newly diagnosed diabetes. The presence of MS or a high score on a model proposed by our group⁵ help us identify patients at high risk for occult diabetes who need an OGTT. The incorporation of a new diagnosis of diabetes will help to improve the residual risk mentioned by Jover et al.¹ by optimizing secondary prevention in these patients.

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