New Guidelines on Metabolic Syndrome

Examining the historical background of metabolic syndrome provides critical insight into its complexity as well as the evolution of its terminology and diagnostic frameworks. The earliest documented observations linking excessive food consumption, obesity, and cardiovascular disturbances date back to ancient Egypt, where accounts described sudden cardiac arrest in individuals with elevated body weight. Systematic descriptions of cases resembling the modern understanding of metabolic syndrome likely emerged in the 17th and 18th centuries, but it was not until the 20th century that scientific research began to systematically explore the relationships between lifestyle factors and the development of metabolic disorders—including insulin resistance, dyslipidemia, and hypertension. Earlier attempts to classify this cluster of conditions employed terms such as "triad syndrome" or "syndrome of affluence," reflecting contemporaneous perceptions of socioeconomic causes. The formal designation "metabolic syndrome" was proposed in 1981 by German researchers, with its initial definition encompassing the co-occurrence of obesity, type 2 diabetes, hyperlipidemia (elevated total cholesterol and triglyceride levels), hypertension, and gout—conditions that significantly increase the risk of coronary artery disease and renal calculi. Over subsequent decades, various medical organizations, including the World Health Organization (WHO), the International Diabetes Federation (IDF), and the American Heart Association (AHA), developed distinct diagnostic criteria that varied in both selected parameters and threshold values. The most recent consensus, published in 2009 by the IDF in collaboration with the AHA and the National Heart, Lung, and Blood Institute (NHLBI), establishes that metabolic syndrome may be diagnosed when at least three of five criteria are met: (1) abdominal obesity (waist circumference ≥ 94 cm in men and ≥ 80 cm in women for European populations), (2) hypertriglyceridemia (≥ 150 mg/dL or triglyceride-lowering therapy), (3) low HDL cholesterol (< 40 mg/dL in men and < 50 mg/dL in women or HDL-raising treatment), (4) elevated blood pressure (≥ 130/85 mmHg or antihypertensive therapy), and (5) elevated fasting glucose (≥ 100 mg/dL or glucose-lowering treatment).

In light of the substantial advancements in medical knowledge observed over recent years, a consortium of Polish scientific societies and research institutions formally introduced revised diagnostic criteria for metabolic syndrome in 2022. The foundational, non-negotiable prerequisite for diagnosis remains the confirmation of obesity—defined either as a body mass index (BMI) of 30 kg/m² or greater, or a waist circumference measuring at least 88 centimeters in females and 102 centimeters in males. Additionally, the presence of at least two of the following three abnormalities is mandatory for diagnostic confirmation: 1. Impaired glucose metabolism—evidenced by fasting plasma glucose concentrations ≥ 100 mg/dL, postprandial hyperglycemia (≥ 140 mg/dL at 120 minutes during an oral glucose tolerance test), elevated glycated hemoglobin levels (≥ 5.7%), or the requirement for glucose-lowering pharmacotherapy; 2. Arterial hypertension—diagnosed when systolic and/or diastolic blood pressure values reach ≥ 130/85 mmHg in clinical settings or ≥ 130/80 mmHg in home measurements, or when antihypertensive treatment is administered; 3. Dyslipidemia marked by elevated non-high-density lipoprotein cholesterol (≥ 130 mg/dL) or the use of lipid-modifying agents. Furthermore, building upon research conducted by Professor Piotr Dobrowolski’s team (2022), experts have delineated a spectrum of frequently co-occurring clinical features that, while not essential for diagnosis, may indicate advanced pathological progression. These include: renal dysfunction of varying severity, non-alcoholic fatty liver disease, obstructive sleep apnea, heart failure with preserved ejection fraction, polycystic ovary syndrome (PCOS), low-grade chronic inflammation, sympathetic nervous system overactivation, and hyperuricemia—an elevated serum uric acid concentration.

This document provides a structured comparison and critical evaluation of the diagnostic criteria for metabolic syndrome as established by leading international medical societies, alongside an innovative diagnostic proposal developed by a team of Polish researchers—including the 2014 publications by M. Kramkowska and K. Czyżewska, as well as the subsequent 2022 study by P. Dobrowolski and colleagues, which introduces significant modifications relative to prior consensus guidelines.

Disorders of carbohydrate metabolism encompassing: impaired glucose tolerance, abnormal fasting glycemia, or established type 2 diabetes mellitus. Additionally, at least two of the following coexisting conditions must be present: • excessive accumulation of visceral adipose tissue (central or abdominal obesity), • dysregulated lipid profile (elevated circulating triglyceride concentrations coupled with reduced high-density lipoprotein cholesterol levels), • hypertensive blood pressure readings, • urinary excretion of microalbumin (microalbuminuria).

The metabolic syndrome is identified under the 1999 EGIR criteria by the presence of insulin resistance (elevated fasting insulin levels) alongside at least two of the following clinical features: • abdominal (central) obesity, • lipid metabolism disorders (dyslipidemia), • elevated arterial blood pressure or ongoing antihypertensive treatment, • impaired glucose tolerance (IGT) or impaired fasting glucose (IFG), provided that overt type 2 diabetes mellitus has been excluded from the diagnosis.

A clinical state defined by impaired glucose tolerance or abnormal fasting plasma glucose levels in the absence of confirmed type 2 diabetes mellitus. Concomitantly, at least one of the following risk factors must be present: • excess body weight (BMI ≥25 kg/m²) or obesity (BMI ≥30 kg/m²), • lipid metabolism disorder (dyslipidemia) characterized by elevated triglyceride concentrations or reduced high-density lipoprotein (HDL) cholesterol, • elevated blood pressure readings (≥130/85 mmHg), • first-degree family history of type 2 diabetes, • diagnosed polycystic ovary syndrome (PCOS), • physical inactivity (sedentary lifestyle), • age exceeding 40–45 years (with population-specific variations).

Metabolic syndrome is identified when central (abdominal) obesity—defined by population- and gender-specific waist circumference thresholds—coexists with at least two of the following abnormalities: elevated triglyceride concentrations (≥ 150 mg/dL) or pharmacologic treatment for this condition, reduced high-density lipoprotein (HDL) cholesterol levels (< 40 mg/dL in men, < 50 mg/dL in women) or therapy aimed at increasing HDL, elevated blood pressure (≥ 130/85 mmHg) or antihypertensive medication use, and elevated fasting plasma glucose (≥ 100 mg/dL) or previously diagnosed type 2 diabetes mellitus.

The diagnostic criteria for metabolic syndrome necessitate the presence of at least three of the following abnormalities—or their ongoing pharmacological management: • abdominal (visceral) obesity characterized by excessive central fat deposition, • elevated circulating triglyceride concentrations (hypertriglyceridemia) or active lipid-lowering treatment, • reduced high-density lipoprotein (HDL) cholesterol levels (often referred to as "beneficial cholesterol") or therapeutic intervention, • sustained arterial hypertension (elevated blood pressure) or antihypertensive medication use, • impaired fasting glucose (hyperglycemia) or glucose-modulating therapy.

According to unified consensus criteria, a diagnosis of metabolic syndrome requires the presence of abdominal obesity along with at least two of the following clinical components: – Impaired fasting glucose (≥ 100 mg/dL), impaired glucose tolerance, elevated glycated hemoglobin (HbA1c), or pharmacological treatment for diabetes; – Elevated blood pressure (systolic ≥ 130 mmHg and/or diastolic ≥ 85 mmHg) or antihypertensive therapy; – Elevated serum triglycerides (≥ 150 mg/dL) or specific lipid-lowering treatment; – Reduced HDL cholesterol (< 40 mg/dL in men, < 50 mg/dL in women) or elevated non-HDL cholesterol. Most major cardiovascular and endocrinology associations converge on these core risk parameters. A notable update in recent guidelines is the formal incorporation of glycated hemoglobin (HbA1c) as a diagnostic indicator of carbohydrate dysregulation, reflecting glycemic control over preceding months. Furthermore, non-HDL cholesterol is emphasized as a superior marker of total atherogenic lipoprotein burden. Importantly, receiving pharmacotherapy for any component confirms its presence, as ongoing medical management does not eliminate baseline cardiovascular risk.

The comprehensive management of metabolic syndrome (MetS) necessitates multidimensional lifestyle modifications, encompassing evidence-based nutritional strategies, structured physical activity regimens, optimization of sleep architecture, and the cessation of harmful substances such as tobacco and alcohol. Below are the detailed dietary guidelines for individuals diagnosed with MetS, accompanied by clinically validated outcomes stemming from their implementation (derived from Dobrowolski et al., 2022). It is critical to emphasize, however, that these recommendations must be individually tailored to account for the heterogeneous health statuses, physiological capacities, and psychological profiles of patients.