Metabolic syndrome in Indian children - An alarming rise.

In 1988 Gerald Reaven and colleagues described the ‘Metabolic Syndrome’ as a link between insulin resistance and hypertension, dyslipidemia, type 2 diabetes mellitus, and other metabolic abnormalities associated with an increased risk of atherosclerotic cardiovascular disease in adults (1) . Although many criteria are in vogue for definition of MS in adults, there is a lack of consensus on the definition of MS in children which is mostly defined in various populations using different criteria and cut offs (2) . Even though prevalence rates vary depending on diverse criteria used in the pediatric age group and despite lack of uniform definition, various investigators have convincingly shown that MS develops and is highly prevalent during childhood particularly in obese children (34) . In view of the high and increasing prevalence of obesity and type 2 diabetes mellitus in children and adolescents, there is an urgent need to establish internationally accepted criteria for the diagnosis of MS. It has been debated that ethnic differences in obesity and metabolic parameters should be considered in the definition of MS in children. Proposed ATP III guidelines for MS in children are: 1) Hypertriglyceridemia >= 90th percentile. 2) Low HDL <= 10th percentile for age and sex 3) High fasting blood glucose >= 6.1 mmol/litre 4). Central obesity >=90th percentile for age and sex. 5) Hypertension >= 90th percentile for age, sex and height. If three or more components are present, diagnosis of MS is made.

Although obesity is the central factor in the pathogenesis of insulin resistance, other associated factors like hypertension, dyslipidemia and sub-clinical inflammation are more likely to be consequences of MS in children (5) . About one third of overweight or obese children and adolescents exhibit features of MS (6) . Thus children and adolescents with BMI greater than or equal to the 95th percentile for age and sex should undergo an in-depth medical assessment. Use of the 95th percentile identifies children with a significant likelihood of persistence of obesity into adulthood. In older adolescents, BMI above the 95th percentile is associated with elevated blood pressure and lipid profiles that increase the risk of obesity-related disease and mortality. Children who fit these criteria should be evaluated carefully, as described below, and treated unless some contraindication is found. A child whose BMI falls between the 85th and 95th percentile for age and sex should be evaluated care-fully with particular attention to secondary complications of obesity including hypertension and dyslipidemia. A recent large change in BMI should also prompt evaluation and possible treatment. Although the degree of change that indicates risk has not been defined, an annual increase of 3 to 4 BMI units probably reflects rapid increase in body fat in most children. This estimate is based on the observation that a BMI in a given percentile channel increases annually by #1 unit, but for most age groups, the BMI at the 85th percentile is 3 or 4 units higher than the BMI at the 50th percentile.

As compared to Caucasians, adult Asian-Indians have lower BMI (body mass index), waist circumference and muscle mass but hyperglycemia, Hypertriglyceridemia and hypertension appear at lower levels of BMI and waist circumferences (7) . The reasons are unclear although body fat patterning appears to be important for the genesis of the metabolic perturbations in South Asians (8) . Insulin resistance is considered to be central factor in the pathophysiology of MS and dysglycemia and the prevalence of both is on rise world over (9) . The high prevalence of insulin resistance in Asian Indian children who are undergoing nutritional and lifestyle transitions rapidly, is a worrisome feature (10) . Dyslipidemia has been characterized by high triglycerides, low HDL and high LDL (11) .High triglycerides with other features of atherogenic dyslipidemia have been commonly found in urban Asian Indians (12) . Dyslipidemia in Asian Indians has been attributed to a multitude of factors, including physical inactivity, carbohydrate rich diet, abnormal body composition in particular excess truncal fat and increased intra abdominal fat and genetic predisposition. Interestingly nearly 70% of adolescent and school children studies in Delhi schools were physically inactive in the 10th and 12th classes, in which important academics are held. Hypertension is the weakest correlate of insulin resistance. It has been postulated that hyperinsulinemia secondary to insulin resistance leads to increase in renal retention of sodium and also increases sympathetic activity, which causes elevation of blood pressure (13) . Polycystic ovarian syndrome (PCOS) is now known to be strongly associated with insulin resistance and MS. A higher prevalence of PCOS was reported in South Asian women than in white Caucasians (14) . Non alcoholic fatty liver disease sometimes resulting in non alcoholic steato –hepatitis and occasionally cryptogenic cirrhosis has been shown to be important hepatic correlate of MS (15) . Significant heritability and pleiotropy seen for the components of MS indicate strong genetic contribution (16) . A graded increase in insulin resistance, type 2 diabetes mellitus and other cardiovascular risk factors has been seen when rural people move to urban areas in developing countries (17) . South Asians appear to be highly susceptible to MS, which needs further discussion. Although mean ponderal index was found lower in South Asian children than in white Caucasians, mean fasting and post glucose load insulin concentration and serum triglyceride levels were higher (18) . Our study also showed higher triglyceride and low HDL as the commonest components of MS prevalent in Kashmiri children (unpublished). There is a need for integrated definition of MS in children and adolescents, taking cognizance of the ethnic specific variations. Obesity and body fat patterning are important determinants of insulin resistance and MS of children and ethnic variations in these parameters are seen. Excessive body fat and thicker truncal subcutaneous fat are important predisposing factors for development of insulin resistance in South Asian children. Because the MS tracks into adult hood, its manifestations need to be recognized early for prevention of diabetes and coronary artery disease. Therapeutic life style changes, maintenance of high level of physical activity and normal weight and education of teachers and parents about MS are most important strategies. In our valley the knowledge about metabolic syndrome and its consequences is virtually nil even among doctors not to talk about general mass, so our goal should be to aware of the problem. Thus education should be given at the personal level, family level, community level and school level. Print media, electronic media all should be involved. Our motive should be such that prevention should be of the primordial type rather than primary or secondary type. Thus our plan should be prevention of the emergence of risk factors. Pharmacological therapy for individual components of MS should be the last resort.