CHAPTER ONE
INTRODUCTION
Metabolic syndrome refers to a group of metabolic abnormalities that confer risk of cardiovascular disease and diabetes mellitus. It was first described as a clinical entity in 1988 by Reaven although it has much older origin having been observed as early as 1923 by Kylin. However it has assumed great prominence in clinical discourse in the past decade. This is basically due to its central role as a cluster of risk factors for cardiovascular disease (CVD) and type 2 diabetes mellitus (DM) (Ford, 2005).
When it was first described, this syndrome was an ill-defined cluster comprising hyperglycaemia, hyperuricaemia, dyslipidaemia and hypertension, but has undergone various modifications over the years. Over the years, it has been called various names; Reaven’s syndrome, syndrome X, dysmetabolic syndrome, cardiometabolic syndrome, plurimetabolic syndrome, insulin resistance syndrome and the deadly quartet (Alberti et al., 2009).
The criteria for metabolic syndrome have evolved since the original definition by the World Health Organization in 1999, reflecting growing clinical evidence and analysis by a variety of consensus conferences and professional organizations. According to National Cholesterol Education Programme-Adult treatment Panel III (NCEP-ATP III, 2012), a diagnosis of metabolic syndrome is made when three or more of the following conditions are present in an individual: central obesity (waist circumference > 102 cm for males or > 88 cm for females), hypertriglyceridaemia (triacylglycerol ≥ 150 mg/dL), low level of high density lipoproteins (HDL < 40 mg/dL for males and < 50 mg/dL for females), hypertension (systolic blood pressure > 130 mmHg or diastolic blood pressure > 85 mmHg), or hyperglycemia (fasting blood glucose > 100 mg/dL) (NCEP-ATP III, 2012).
1.1 Epidemiology of Metabolic Syndrome
The prevalence of metabolic syndrome varies around the world, in part reflecting the age and ethnicity of the populations studied and the diagnostic criteria applied. In general, the prevalence of metabolic syndrome increases with age. The highest recorded prevalence worldwide is in Native Americans, with nearly 60% of women ages 45–49 and 45% of men ages 45–49 meeting National Cholesterol Education Program and Adult Treatment Panel III (NCEP:ATP III) criteria (Ford, 2005).
In the United States, metabolic syndrome is less common in African-American men and more common in Mexican-American women. Based on data from the National Health and Nutrition Examination Survey (NHANES) 1999–2000, the age-adjusted prevalence of the metabolic syndrome in United States adults who did not have diabetes is 28% for men and 30% for women (Ford et al., 2002).
In France, a cohort study of 30 to 60 years old has shown< 10% prevalence for each sex, although 17.5% are affected in the age range 60–64. Greater industrialization worldwide is associated with rising rates of obesity, which is anticipated to increase prevalence of the metabolic syndrome dramatically, especially as the population ages. Moreover, the rising prevalence and severity of obesity in children is a feature of the metabolic syndrome in a younger population (DeFronzo and Ferrannini, 1991).
In Nigeria, a study conducted in Ibadan showed prevalence of metabolic syndrome to be 15% for women and 19% for men (Nwegbu and Jaiyesimi, 2012). Another study in Nnewi showed that among newly diagnosed diabetes mellitus patients, metabolic syndrome prevalence was 67%; of which 58% were women and 42% were men (Osuji et al., 2012).
