A systematic review of 24 studies found sex-related differences in how men and women respond to insulin therapy, but the evidence quality is low and patterns vary significantly by diabetes type and treatment setting. These results are hypothesis-generating rather than practice-changing at present.
Researchers from the BMJ conducted a comprehensive systematic review examining whether biological sex influences glycemic control and insulin requirements in people with diabetes. They searched four major databases through December 2025 and included 24 randomized and observational studies involving adults receiving insulin therapy. Using the GRADE framework to assess evidence certainty, they extracted data on HbA1c targets, time-in-range, hypoglycemia risk, and insulin dosing.
The findings diverged sharply between type 1 and type 2 diabetes. In type 1 diabetes, women and men showed no meaningful difference in achieving HbA1c below 7% (RR 1.05, 95% CI 0.91 to 1.22; very low certainty). Women did show a trend toward higher time-in-range, though this finding carried moderate certainty and the confidence interval crossed zero, suggesting uncertainty. For type 2 diabetes, men were more likely to achieve HbA1c targets compared to women (RR 0.86), though this finding was rated low certainty. A more robust observation emerged in insulin dosing: women required higher weight-adjusted insulin doses than men in type 2 diabetes (SMD 0.55, 95% CI 0.23 to 0.86; very low certainty).
Hypoglycemia patterns presented a puzzling picture with substantial heterogeneity across studies. In inpatient settings, women showed numerically lower hypoglycemia risk (RR 0.78), while in outpatient settings the direction reversed slightly (RR 1.08), though neither reached statistical significance and both were rated very low to low certainty. The authors emphasized that I-squared values exceeded 70%, indicating inconsistency that suggests multiple unmeasured factors drive these differences across different study populations and contexts.
The review's most honest conclusion acknowledges its limitations: the certainty of evidence is predominantly very low to low, and substantial heterogeneity makes it impossible to determine whether the observed patterns reflect true biological sex differences or emerge from differences in study design, populations, lifestyle factors, medication adherence, body composition, or other confounders. The authors explicitly state these findings should be interpreted as hypothesis-generating rather than actionable for clinical decision-making.
If you take insulin for diabetes, this research doesn't yet translate into specific changes to your management strategy. The findings highlight an important blind spot in diabetes research: most studies don't systematically compare outcomes between men and women with adequate controls for lifestyle, diet, exercise, stress, and medication adherence. Until future studies rigorously isolate sex as a variable from these other factors, clinicians should continue personalizing insulin therapy based on individual response rather than assuming sex-based protocols work universally.
The weight-adjusted insulin dose difference in type 2 diabetes is the most concrete observation here. If you're a woman with type 2 diabetes, this suggests you might require careful dose titration rather than assuming standard dosing charts derived from mixed populations will fit your needs. Work with your provider to find your individual insulin requirement through systematic adjustment and glucose monitoring.
The heterogeneity across settings (inpatient vs outpatient) suggests that real-world context matters enormously. Stress levels, meal timing, physical activity, and medication access differ dramatically between hospital and home environments, which likely explains why hypoglycemia patterns reversed between settings. This reinforces that diabetes management requires attention to your specific circumstances, not generic recommendations.
| Parameter | Details |
|---|---|
| Study type | Systematic review and meta-analysis |
| Number of included studies | 24 (randomized and observational) |
| Population | Adults (both sexes) receiving insulin therapy for type 1 or type 2 diabetes |
| Primary outcomes | HbA1c achievement, time-in-range, hypoglycemia risk, insulin dose requirements |
| Evidence assessment | GRADE framework |
| Key certainty ratings | Very low for HbA1c targets; moderate for type 1 time-in-range; low for type 2 HbA1c; very low for dosing |
| Heterogeneity | Substantial (I2 >70% for hypoglycemia outcomes) |
| Published | BMJ Open Diabetes Research & Care |
| Registry | CRD420251144696 |
Systematic review examining sex differences in glycemic outcomes with insulin therapy (2025). *BMJ Open Diabetes Research & Care*. PubMed: 42020119
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