Relationships between serum irisin levels and metabolic parameters in Japanese patients with obesity

Abstract

SummaryBackground/PurposeIrisin is a skeletal muscle myokine that causes the brown coloration of white fat, promotes fat burning, inhibits weight gain and may be useful for treatment of obesity. Irisin is also related to glucose/lipid metabolism and may prevent onset of diabetes, but a consensus on irisin secretion has not been reached. The purpose of this study was to determine the relationships between serum irisin levels and physical factors in untreated Japanese men and women with obesity.MethodsThe subjects were 66 untreated patients with obesity (body mass index ≥30 kg m−2) who visited our obesity clinic. The subjects included 19 men and 47 women with a mean age of 45.7 ± 13.4 years, mean body weight of 93.8 ± 17.6 kg, and mean body mass index of 36.5 ± 4.7 kg m−2. At the initial visit, blood sampling was performed, body composition was evaluated using dual energy X‐ray absorptiometry, and exercise tolerance was determined in a cardiopulmonary exercise test. Homeostasis model of assessment – insulin resistance (HOMA‐IR), an index of insulin resistance, and the serum level of irisin were measured.ResultsIn men, serum irisin was positively correlated with fasting blood glucose (r = 0.491, P < 0.05), immunoreactive insulin (r = 0.536, P < 0.05), HOMA‐IR (r = 0.635, P < 0.01), body weight (r = 0.491, P < 0.05), lean body mass of the trunk (r = 0.579, P < 0.05) and whole lean body mass (r = 0.489, P < 0.05). In women, serum irisin was positively correlated with immunoreactive insulin (r = 0.502, P < 0.01) and HOMA‐IR (r = 0.385, P < 0.01). In both sexes, HOMA‐IR was an independent variable associated with obesity (men: β = 0.635, R2 = 0.369, P < 0.01; women: β = 0.385, R2 = 0.129, P < 0.01).ConclusionThe serum level of irisin was positively correlated with HOMA‐IR in Japanese patients with obesity of both sexes. This suggests that compensatory enhancement of irisin secretion may occur in response to insulin resistance.

Irisin and markers of metabolic derangement in non-diabetic Caucasian subjects with stage I-II obesity during early aging

“…Conversely, in our Caucasian cohort in the early stages of aging, the association between irisin, insulin levels and HOMA index was significant in both genders, in agreement with previous reports in younger Asian populations [21] and with the meta-analysis by Qiu et al [10]. In our series, sex differences were maintained across IR severity stages.…”

“…Gender-differences in irisin levels have been observed: women consistently displaying higher values than men among Saudi children [19], middle-aged Chinese [20] and Japanese adults [21]. The divergent results from studies performed in healthy, non OB, and young population [22,23] may be ascribed to the physiologically higher muscle mass in males compared to females, in the absence of increased excess body fat.…”

Irisin and Autophagy: First Update

“…To this end, Al-Daghri et al observed negative association between irisin and fasting glucose and HOMA-IR in school-age Saudi boys and girls [ 63 ]. Conversely, there are positive associations between irisin and insulin concentration, fasting glucose, and HOMA-IR [ 64 , 65 , 66 , 67 ]. Fukushima et al analyzed a positive correlation on obese men and adult women [ 66 ], while Pardo et al determined a correlation in women with anorexia nervosa, normal weight, and obesity [ 65 ].…”

Research update for articles published in EJCI in 2014

“…Animal studies also demonstrated the effects of female sex hormones in irisin levels among ovariectomized female rats, but not in orchidectomized male rats [23]. Furthermore, the association of irisin levels in glycemic metabolism is reinforced in several recent studies, with elevated irisin levels being an independent predictor of diabetes mellitus and Homeostatic Model Assessment -Insulin Resistance (HOMA-IR) in adults [24,25]. The association of irisin however to insulin resistance is positive in adults as opposed to inverse association in children in our 2014 study.…”