Predictors of cardiovascular risk among patients with type 1 diabetes: A critical analysis of the metabolic syndrome and its components

Patients with type 1 diabetes (T1D) are at increased risk for cardiovascular diseases. The metabolic syndrome (MetS), a complex disorder defined by a cluster of interconnected factors including abdominal obesity, hypertension, dyslipidaemia and insulin resistance, has been proposed to identify patients with T1D at high cardiovascular risk. The MetS has been identified in 8-45% of patients with T1D, depending on the definition and cohort studied. However, clinicians and researchers face several issues with the criteria for MetS in patients with T1D, therefore questioning its value in routine care. For example, three criteria can lead to overestimation of MetS prevalence; the impaired fasting glucose criterion is irrelevant as it is automatically fulfilled; and the widespread use of antihypertensive and lipid-lowering medications for cardiac and renal preventative purposes can contribute to overestimations of the prevalence of raised blood pressure and elevated triglycerides. In cross-sectional studies, the MetS has been associated mostly with an increased risk of microvascular complications whereas, in prospective cohorts, the predictive value of MetS for micro- and macrovascular outcomes has been inconsistent. While identifying diabetes patients at increased risk for cardiovascular complications and early mortality is crucial from a prevention standpoint, for patients with T1D, the current definition of MetS may not be the most suitable tool. The aims of the present report are to review the applicability and limitations of the MetS in patients with T1D, and to discuss alternative avenues to identify high-risk patients.