Women have greater (Metabolic) Stress Response than Men

Objective:
Stress hyperglycaemia is frequent in intensive care unit (ICU) patients and associated with increased morbidity and mortality. Glycemic control (GC) has proven difficult due to high levels of inter- and intra- patient variability in response to insulin. However, despite anecdotes, no one has studied if males and females are easier/harder to control. This study examines differences in clinically validated insulin sensitivity (SI) and its variability between males and females as surrogates of control difficulty.
Method:
Data from N=145 SPRINT GC patients is analysed for the first 72hours of stay. Demographic characteristics of the male (N=91) and female (N=54) sub-cohorts are similar (age, mortality, injury severity, ICU length of stay, GC duration), as well as GC outcomes (median BG, %BG in/out target band, workload). SI is identified hourly and its hour-to-hour percentage variability is computed (%ΔSI). Due to large data samples, the 95%CI of difference in bootstrapped medians in SI and %ΔSI is used for hypothesis testing to a significance level of p<0.05. Equivalence testing is used to determine whether this difference is clinically significant.
Results:
Females are more insulin resistant (lower SI) than males (2.5e-4[1.5e-4 4.0e-4] vs. 3.1 e-4[1.7e-4 5.5e-4] L/mU/min). This difference is statistically different and clinically not equivalent. Conversely, %ΔSI is not significantly different (2[-17 22]% vs. 3[-14 25]%), and any difference can be considered clinically equivalent. These observations are also true when data is analysed over 6-h blocks.
Conclusions:
Females are more insulin resistant than males but have equivalent SI variability. The difference in SI levels suggests either higher endogenous glucose production and/or lower insulin secretion rates for females. Since severity of injury and glycemic outcomes are similar across both groups, the results suggest a stronger stress response to injury for female patients.