Insulin resistance is higher in prepubertal girls but switches to become higher in boys at age 16: A Cohort Study (EarlyBird 57).
BACKGROUND
The risk of type 2 diabetes is increasing in teenage girls, and is associated with their greater insulin resistance (IR).


HYPOTHESIS
We hypothesized that the adverse metabolic profile of girls (compared with boys) would persist from childhood through adolescence.


PATIENTS AND METHODS
Community-based longitudinal cohort of 292 children (147 boys) studied annually from 9 to 16 years.


MEASURES
IR (homeostasis-model-assessment-2), high-density lipoprotein-cholesterol (HDL-C), triglycerides, % body-fat (dual-energy x-ray absorptiometry), pubertal stage (age at peak height velocity), physical activity (accelerometry). Multi-level modelling established the age-related trends in IR and lipids and the influence of covariates.


RESULTS
Each year from 9 to 15 years, girls had 21% to 63% higher IR than boys (girls mean IR 0.73-1.33, boys 0.51-0.89, P < .005). At 16 years the gender difference was not significant (girls IR 0.60, boys 0.56, P = .45). Girls had lower HDL-C from 9 to 12 years, higher triglycerides from 9 to 14 years, greater adiposity throughout, and earlier puberty, but boys were more active than girls (all P < .05). After adjustment for %-fat, puberty and activity, the gender difference in IR between girls and boys aged 9 to 15 years became non-significant (IR girls 0.66-1.01, boys 0.65-1.04, P > .07). However, after adjustment at 16 years, girls' IR was 25% lower than boys' (girls 0.44, boys 0.63, P = .001), and they had 22% higher HDL-C (P < .001) and 20% lower triglycerides (P = .003).


CONCLUSIONS
The higher IR of prepubertal and early pubertal girls diminishes during late puberty, and boys begin to exhibit greater metabolic risk. Despite being leaner and more active, boys at 16 years have higher IR than girls, suggesting future higher risk for diabetes, thus we reject our hypothesis.
['Jeffery|Sarah C|SC|', 'Hosking|Joanne|J|', 'Jeffery|Alison N|AN|0000-0001-7539-5957', 'Murphy|Michael J|MJ|', 'Voss|Linda D|LD|', 'Wilkin|Terence J|TJ|', 'Pinkney|Jonathan|J|']
D015502:Absorptiometry, Photon D050154:Adiposity D000293:Adolescent D002648:Child D008076:Cholesterol, HDL D015331:Cohort Studies D003924:Diabetes Mellitus, Type 2 D004739:England D015444:Exercise D005260:Female D006801:Humans D007333:Insulin Resistance D008137:Longitudinal Studies D008297:Male D011627:Puberty D012306:Risk D012574:Schools D012727:Sex Characteristics D012737:Sex Factors D014280:Triglycerides
insulin resistance adolescent physical activity adiposity child