Introduction: Metabolic syndrome (MetS) is described as a cluster of several commonly occurring disorders including abdominal obesity, hypertension (HT) (≥ 130/85 mm Hg), carbohydrate disorders: impaired fasting glucose or type 2 diabetes mellitus and lipids disorders such as hypertriglyceridaemia (TG), and low levels of high-density-lipoprotein cholesterol (HDL-C). Insulin resistance (IR) is defined as a glucose homoeostasis disorder involving a decreased sensitivity of muscles, adipose tissue, liver, and other body tissues to insulin, despite its normal or increased concentration in blood.
Material and methods: The study group included 424 subjects with MetS (260 females, 164 males). All patients were recruited for 24 months from the Internal Ward of the District Hospital in Wąbrzeźno, Poland and the Department of Endocrinology and Diabetology Collegium Medicum in Bydgoszcz, Poland. The diagnosis of the MetS was made on the basis of International Diabetes Federation (IDF) criteria. MetS diagnosis was established when three or more criteria were met. To evaluate and measure IR, a hyperinsulinaemic-euglycaemic clamp was performed in each patient. IR was also determined through HOMA-IR.
Results: All patients of the study group were diagnosed with obesity, 73.5% with high fasting glucose levels, 66.9% with HT, 48.3% with lower level of HDL-C, and 38.2% with TG. It did not have an influence on the IR results. The study group was divided into 6 subgroups according to the constellation of 3 particular components of MetS (O + DM2T + ↑TG; O + HT + DM2T; O + DM2T + ↓HDL-C; O + HT + IFG; O + HT + ↑TG and O + HT + ↓HDL-C). IR of different degree was diagnosed in all patients of the study group. The results of our study showed that the highest IR was observed in patients with central obesity accompanied by DM2T and ↑TG. Also in subgroups with DM2T and HT or DM2T and ↓HDL-C, a high index of IR was noticed.
Conclusions: The occurrence of IR in patients with MetS is obvious. However, despite the fact that they are high or very high cardiovascular risk patients, they are not a homogeneous group. Such patients differ from each other depending on the presence and constellation of particular disorders that make up the diagnosis of the MetS. Patients with MetS are a heterogeneous group differing in degree of IR and the risk of CVD.
Keywords: diabetes mellitus; insulin resistance; metabolic syndrome; obesity.