Sex and Seasonal Variation in Blood Glucose Among Trauma Patients: A Retrospective Laboratory Study from Benghazi, Libya

Abstract

Blood glucose concentration varies with biological sex and time of year, yet population-level data from North Africa are scarce. Often, evidence derives from laboratory records where sampling methods are poorly described. This study examined sex and seasonal variations in blood glucose within a Libyan hospital population. A retrospective, cross-sectional analysis was conducted on 4,939 blood glucose measurements recorded during 2018 at Al-Jala Hospital for Surgery and Accidents, Benghazi. The study utilized available covariates, specifically sex and month of collection. Analyses included descriptive statistics, Welch-corrected t-tests, one-way and two-way analysis of variance, Games-Howell post-hoc comparisons, and effect size calculations. The mean blood glucose was 125.60 mg/dL (SD 65.90; range 24–719). Levels were significantly higher in female than male patients (129.51 vs. 123.42 mg/dL; mean difference 6.09, 95% CI 2.07–10.11; p = .003). Seasonal variation was observed (F(3, 4935) = 4.55, p = .003) with no significant interaction (p = .673). Effect sizes were small (partial eta-squared of 0.0016 for sex and 0.0023 for season; Cohen’s d of 0.093). Post-hoc tests revealed significant differences only between winter and spring, and winter and autumn. The marked monthly variation in record volume (range 67–754) suggests that the seasonal pattern reflects differences in sampling frequency rather than physiological fluctuations. These findings underscore the limitations of interpreting retrospective laboratory data without accounting for ascertainment bias.