Whole-body metabolic flexibility (MF), i.e., switching substrate oxidation between fasting and fed states often becomes abnormal with insulin resistance (IR). Data regarding MF in women with PCOS, whom often have IR, are mixed and confounded by varied diets and habitual physical activity. No study has assessed MF in response to a multi-phase hyperinsulinemic-euglycemic clamp in PCOS females relative to non-PCOS with similar habitual physical activity and controlled diet. Adolescent girls with obesity and PCOS (age 14.9 ± 1.5 years; BMI 35 ± 4 kg/m2), 10 obese controls (age 13.5 ± 1.3; BMI 32 ± 2) and 13 normal BMI PCOS (age 16.2 ± 1.5; BMI 22.8 ± 2) were included. All girls were sedentary per questionnaire and 7 day accelerometry. A 4-phase hyperinulinemic-euglycemic clamp (basal, 10, 16 and 80 mU/m2/min of insulin) including glucose and glycerol tracers was performed. Glucose rate of disappearance (Rd), glycerol rate of appearance (Ra) and respiratory quotient (RQ) were assessed during each clamp phase. MF was defined as a change in RQ from baseline to each phase (ΔRQ). Basal RQs were not different between groups. Lean PCOS had higher ΔRQ at phase 10 compared to obese PCOS (p=0.005) and obese controls (p=0.003). All groups had similar ΔRQs at 16 and 80 phases. In multivariable regression models, Δ 10 glycerol Ra (Δ from baseline to 10 phase) was associated with phase 10 ΔRQ, independent of age and BMI (p=0.04); Δ 80 glycerol Ra and Δ 80 glucose Rd were associated with phase 80 ΔRQ, independent of age and BMI (p=0.048). Sedentary obese adolescents regardless of PCOS status have lower MF compared to lean PCOS during the low insulin dose which was associated with whole body lipolysis. However, this difference is not found during the high insulin dose, suggesting obese girls have only subtle defects in MF. Further, PCOS is not associated with lower MF once diet and habitual activity are matched.
P. Wiromrat: None. C.A. Rynders: None. K.J. Nadeau: None. M. Cree-Green: None.
American Diabetes Association (7-11-CD-08 to K.J.N.); American Heart Association (13CRP14120015); Thrasher Research Fund; National Center for Research Resources Colorado (TL1TR002533); Pediatric Endocrinology Society; National Institute of Diabetes and Digestive and Kidney Diseases (T32DK063687, K23DK107871)