**4.1. Lipid profile**

when compared with CT and overweight (OW) subjects [25, 32]. However, contradictory data

Cardiometabolic risk factors, such as dyslipidaemia, hyperglycaemia, hypertension, central obesity and IR, tend to cluster and are associated with increased risk for cardiovascular diseases (CVDs) [1, 2]. These risk factors are already altered in early ages in OB individuals, and changes in adiponectin levels may underlie such risk. Indeed, an association of adiponectin with metabolic risk factors [1, 34] has been reported, leading to the proposal of adiponectin as a marker of cardiometabolic risk [24, 35], and as a potential predictor of obesity‐related co‐morbidities [36, 37]. An association between adiponectin levels in childhood and the probability of developing co‐morbidities in the future has been also raised [21]. In agreement, a study by Morrison et al. showed that lower levels of adiponectin in 16‐year‐ old females were related with the development of cardiometabolic risk features at the age of 23 years [38]. Another study also showed adiponectin as a predictor of cardiometabolic risk, in OW children, even when adjusted for age, gender, Tanner stage, BMI, visceral fat

In T2D OB adolescents, adiponectin levels were found to be lower than in normal individuals, and even lower than in OB individuals without T2D. In this population, IR appeared as a main determinant of adiponectin concentrations, more than BMI itself [2]. There are, however, controversial data about the changes in adiponectin, in OB adolescents with and without

In obesity, it is important to consider body fat distribution, besides weight excess. Indeed, increased abdominal obesity has been associated with lower levels of adiponectin [1, 25, 39, 40] and adiponectin was negatively associated with visceral‐to‐subcutaneous fat ratio [41]. The association between hypoadiponectinaemia and increased visceral adipose tissue (VAT)

Younger age of adiposity rebound (AAR) associates with increased adiposity later in life [42, 43]. Nevertheless, no association was found between AAR and adiponectin in 10‐year‐old children, whereas an association was found between AAR and leptin [44]. A preferential relationship of AAR with increased subcutaneous adipose tissue, rather than with VAT, might

In adolescents, the increased abdominal obesity and reduced adiponectin levels are accompanied by enhanced TG and decreased levels of high‐density lipoprotein cholesterol (HDLc) [1], suggesting that central body fat distribution is also associated with a worse control on lipid

The inverse relation of adiponectin with cardiometabolic risk appears to be accepted, especially in pubertal subjects. It is important to highlight that the diagnosis of metabolic syndrome (MS) in young children (under 10 years) should be avoided, as recommended by the International Diabetes Federation, considering the lack of age‐ and gender‐adjusted cut‐offs for MS components and the ambiguous causality evidence in such young ages relating MS

partially explain why no association was found with hypoadiponectinaemia [43].

have also been reported [12, 33].

86 Adiposity - Omics and Molecular Understanding

and IR [34].

T2D [23].

metabolism.

seems to appear early in life [33].

and increased risk of CVD later in life [45].

The effect of adiponectin on lipid metabolism has been widely studied. Adiponectin is known to lower the synthesis of free fatty acids and to stimulate β‐oxidation [46]. Furthermore, HMW adiponectin seems to lower the release of apolipoprotein (apo) B and apo E from the liver, decreasing the release of lipoproteins rich in TG (e.g. very‐low‐density lipoprotein (VLDL)) and increasing HDLc levels [47].

The positive association between adiponectin and an improved lipid profile has been confirmed by several data. The most consensual effects for adiponectin are a positive association with HDLc and a negative correlation with TG [1, 13, 27, 29, 48, 49]. These associations are present even in PP ages [26, 50] (**Table 1**). Through its effect on lipid metabolism, adiponectin might even modulate the influence of genetics. Lower levels of apo B/apo A1 ratios and total cholesterol/HDLc were found for individuals with higher adiponectin levels despite presenting an apo E genotype associated with a worse lipid profile [51]. In adolescent OB girls, adiponectin levels were positively associated with HDLc measured 7 years later, highlighting that adiponectin might modulate lipid metabolism even for a long term. However, no correlation was found between adiponectin and TG or low‐density lipoprotein cholesterol (LDLc) [38]. Oppositely, no relation between lipid profile and adiponectin was reported in other paediatric studies [14, 21].


\* , Correlation with total and central adiposity; # , positive correlation with HDL. CT, control; Dyslip, Dyslipidaemia; f, female; IR, insulin resistance; (‐), negative association; NS, not significant; OB, obese; OW, overweight.

**Table 1.** Studies assessing the relation between total adiponectin levels and cardiometabolic risk factors in pre‐pubertal children.

Concerning adiponectin multimers, while LMW adiponectin seems to be linked with a worse lipid profile, through a positive association with TG [5], HMW adiponectin has shown opposite effects [6], even in PP individuals [11].
