The role of gender or sex difference in the development of diabetes complications is debated and a matter of clinical interest, since it may impact the treatment strategies as well as public health policies.
As the Framingham study showed several years ago, diabetic women have a cardiovascular risk 3.5 fold higher than non-diabetic women, while the increase in men is 2.1 fold [11]. However, the baseline cardiovascular risk in men is still higher. Our assessment, using the aforementioned described constrained subcollection from the AMD data, shows that when a first event is recorded, the odds of developing subsequent macrovascular events is consistently higher in women than in men, across almost all age groups, number of years of observation, and specific event sequences.
This is in line with other reports looking at gender differences in subjects with type 2 diabetes and cardiovascular outcomes. Interestingly, a recent meta-analysis systematically comparing adverse cardiovascular outcomes (mainly cardiac and cerebrovascular) in male versus female patients with T2DM following percutaneous coronary intervention (PCI) and including 19,304 patients found that women were more susceptible to short and long-term cardiovascular complications compared to male patients [12].
Our data show that prior to the first cardiovascular event, women have a higher burden of risk factors (e.g., higher cholesterol level, higher BMI). Interestingly, most of the reports comparing women and men with T2DM and established cardiovascular disease in subsequent cardiovascular outcomes, implicated higher baseline comorbidities rate as responsible for higher adverse outcomes in women [13]. In line with these studies, a patient-level pooled analysis of randomized controlled trials showed that among women who underwent PCI with drug eluting stents (DES), chronic kidney disease was associated with a main risk for MACE [14].
In our data, impaired glomerular filtration rate seems to be the main comorbidity worsening in women as compared to men as well as BMI. Women need to attain higher levels of BMI to reach the same levels of visceral and ectopic fat required to become insulin resistant and so to develop diabetes and related complications.
Age, duration of diabetes mellitus, the use of other cardiovascular and oral glucose lowering medications as well as the use of insulin therapy could also have influenced the outcomes between male and female patients with diabetes mellitus. Unfortunately, the medication profile was limitedly reported in these studies.
Women in the AMD cohort tend to get any CVD at an older age. Thus, age could be thought as a confounding risk for the increased risk of a second CVD. However, observing the same lift difference within groups of patients with the same age suggests that the differential gender risk is not influenced by age.
Therapeutic inertia in diabetes refers to the failure of healthcare providers to intensify treatment when patients with diabetes fail to achieve glycemic control or experience complications [15–17]. This lack of treatment escalation can lead to suboptimal outcomes.
Factors contributing to therapeutic inertia include clinical inertia (hesitancy in initiating or intensifying treatment), patient-related factors such as poor adherence to treatment, and healthcare system barriers. Our results suggest highlighting the role of gender disparities in these factors. For example, gender differences in the use of cardioprotective drugs are also implicated as a factor that could adversely affect metabolic and cardiovascular risk factor profiles of women. In our analysis, at baseline, the number of prescribed drugs, either glucose-lowering or cardiovascular agents, seem to be higher in females as compared to males; nevertheless, the number of prescribed cardiovascular drugs was consistently lower for women as compared to men for the following cardiovascular event.
These findings are aligned with data from CVOTs reporting gender disparities in cardiovascular risk management, showing a low percentage of women using cardiovascular protective medications such as ACE inhibitors, statins and aspirin [18].
Another possible cause of women’s additional higher relative risk of second complications is that they could be less aware of their risk of CVD, or they could less likely adhere to treatment once they are at high risk of CVD. An American study found adherence to diabetes medications to be slightly lower amongst women than men [10]. Education and awareness campaigns can help both healthcare providers and patients to better understand the importance of timely treatment escalation.
It would be useful for the future to also understand these aspects. Since most of the evidence-based treatment approval comes from RCT who mostly enrolled men, there is an urgent need to verify if treatments are only tailored to men's clinical needs.
Limitations:
The primary limitation to this study is that our results rely on diagnoses of myocardial infarction, heart failure, ischemic stroke, and PAD reported in the medical charts at the hospitals and not on research data. However, potential minor misclassifications are non-systematic and not gender-biased, and thus, do not influence the overall validity of the analysis.
Furthermore, we cannot rule out that the true cardiovascular events were under or overestimated, which may have biased the results; however, CVD events are in line with those described for the Italian population [19], and generally, our results are concordant with previous studies specifically designed to look at diabetes gender differences on CVD [20]. Secondly, we did not have information on lifestyle and genetic risk factors and adherence to therapy that are potential confounding factors. Lastly, the Italian population is vastly Caucasian, and we did not include immigrating individuals. Thus, our results are not generalizable to non-Caucasian populations.
Strengths
Extracting data from electronic medical records (EMRs) offers a potent research avenue, showcasing notable strengths compared to randomized controlled trials. Such an approach is not new; our team has experience in doing so for over 3 decades [21–23]. The EMR-based data we used, in particular, capitalize on real word patient information, providing us the unique opportunity to view patients' health journeys as compared to other cross-sectional data. This approach allows for the analysis of a large dataset thus enhancing the generalizability of findings.
Unlike the controlled settings of available RCTs or studies specifically designed for specific outcomes, this research reflects the nuances of routine clinical practice, capturing a wealth of information on patient outcomes, treatment patterns and clinician attitudes. However, it is essential to acknowledge limitations such as data quality variations. Nonetheless, the fact that our findings confirm and reflect those obtained in experimental settings make EMR-based studies a valuable complement to the traditional clinical research paradigms.