The glycaemic control was achieved by 63% of primary care diabetic patients aged 40-75 years. Combined controlled targets (HbA1c, BP and LDL), that percentage fall down to 10% and in case we added the BMI<30 kg/m2, it decreased to 6.6%. Women had better glycaemic control (HbA1c) but worst combined targets regardless of the SES index.
Sex was not related with suboptimal glycaemic control when adjusted by covariables but being part of SES quintile 4 and 5 was associated with not reaching the glycaemic goal. When the combined target was analysed being female was related to suboptimal control regardless the SES index and comorbities. Cumulative disadvantage can be seen in women less affluent as they suffer more obesity and hypertension.
Comparison with other studies
In our population, we found that 60.5% of our patients had had their HbA1 checked in the last year. One study in Canada reported that there were 68.9% of patients with a baseline HbA1c assessment at a one-year follow-up (43). However, a study in UK measured the impact of a quality care programme for T2D during 5 years, they started measuring HbA1c in 82.5% of their population in one-year follow-up but they raised this percentage to 99.6% at the end of the study. In their case, only 69% had all the annual measures during the 5 years (20). In our study, high-SES participants were less likely to have an HbA1c measure, which could be explained by patients in that quintile being able to afford private insurance. This contrasts with the UK study where patients belonging to the SES quintile 5 were more likely not to have annual HbA1c monitoring.
Our patients reached the glycaemic target in 63.2%, this finding is concordant to other studies in Spain where patients reached it over 55-60.1% (16,18). Optimal glycaemic target has been described in 62.8% of patients in Norway (44), 52.9% in Canada (14), and 46.7% of patients in the UK (20). A different approach would be to consider optimal glycaemic control if HbA1c was ≤ 8.5 mg/dl, a study in the US found optimal control in 64 % of their patients (45) and in our study it would be 90.4%. It is complicated to compare these percentages when health care access differs so much among countries. By taking into account a global perspective of the disease, we found that sex and SES were related to the achievement of targets. The effect of sex on glycaemic control has been discussed before without clear findings. Some studies suggested that women were more likely to have suboptimal control (18,19) but other studies found the opposite (15,16). Even so, these differences were less than 2% between men and women. In our study, women reached more glycaemic goal than men (64,2% vs 62,4%) but sex was not related to optimal glycaemic control while SES index did. The optimal control decreased in both sexes from the quintile 1 to quintile 5, being on quintile 4 and 5 related to not achieving glycaemic goal. Our results are according to Collier et al (19) and Whyte et al (20), both studies showed how being more deprived was less likely to reach the glycaemic target. These results show that T2D approach should also address social inequalities to try to improve the glycaemic target in those patients more disadvantaged.
Our study evaluated optimal combined control of T2D, compared with Wan et al., who found an optimal combined control in 9.45% of their patients, our result of 10% optimal combined control was similar. However, Braga et al described that 19% of their patients met the three goals (14); that difference is due to doctors who enrolled patients that were given recommendations to follow carefully the guidelines. In Spain, Ibáñez et al. published that patients with a lower SES less frequently reached HbA1c and BP targets, which corresponds with our results (18). However, in our case, patients who achieved the combined target more frequently were those in quintile 5, which could be explained by patients in the quintile 5 visiting their primary care centers more, because of their complications, that those in quintile 1 and 2. Patients in quintile 1 and 2 also could have doctors in secondary care so they received less holistic and longitudinal care. We did not find any study that added BMI<30 kg/m2 to the combined variable; however, we decided to include it because obesity is linked to T2D (46) and to belong to the more deprived quintiles (19), when adding this risk factor a quite poor result appeared, only 6,6% achieved the four targets.
These findings highlight the need for questioning which goals we are chasing when we address T2D. In this study, we focused on the factors that collaborate in not achieving an optimal glycaemic control. We found a positive association between these factors and being female, more deprived and suffering of peripheral arteriopathy or retinopathy. Turning to other studies, Wan et al set the goal in reducing cardiovascular risk, they studied the combined target and suggested that reducing LDL should be the main goal when we failed to achieve them all. In our case, we found we should be prioritizing BP and weight control to achieve glycaemic control. Rodríguez-Gutiérrez et al reviewed the impact of tight glycaemic control in complications and mortality (47). They did not find a benefit on the risk of complications except for a 15% relative-risk reduction of nonfatal myocardial infarction. We should start seeing T2D as a complex disease where research should not address only one target but all of them. Achieving the four targets in our study has been shown unrealistic based on our data. That is the reason why we found how improving BP and BMI control could improve the glycaemic control. We need more data with this approach to understand which targets are more beneficial for the patients. On the other hand, SES perspective should also be taken into account. If we address T2D as an illness where cumulative disadvantage is present (48,49), we will focus in those groups of patients who are more vulnerable.
Our results of cardiovascular complications were similar to those observed in the Penno et al (22) and Tecos cohort (23), where men had more cardiovascular events. This finding could be explained by the use of tobacco (21.9% for men versus 13% for women). However, our study contrasts with Peno and Tecos research (19, 20) about microvascular complications; we found that men had more retinopathy and chronic renal disease, whereas the previous studies observed these complications more frequently in female patients. We reviewed the situation of the chronic kidney disease (CKD) where male have a higher prevalence of the illness, there are a few studies which have similar results to us (32,50,51). They pointed out age, systolic BP, smoking and high albuminuria as risk factors for a decline in the glomerular rate. In our case, men had higher albuminuria and use of tobacco which might explain our results. On the other hand, a meta-analysis (52) revealed the relationship between lower SES and CKD, which is in accordance with our results. About the other microvascular complications, we used EHR to obtain the result of the retinopathy (DR). Most patients are screened and followed in secondary care. This situation could explain that our prevalence is lower than other studies(53,54). A study found that being male and having uncontrolled BP, DM2, BMI and smoking was related to have retinopathy(55), our results are parallel to them.
A meta-analysis conducted by Peters et al. described a higher relative risk of stroke for women with T2D (women: RR: 2.28 (95% CI 1.93-2.69), men: RR: 1.83 (1.60-2.08)) (29). In our study, women had fewer episodes of stroke, which is consistent with a local study (56), where women also had more hypertension and were less likely to smoke. Another point to explain this result relates to age; our population was between 40-75 years old, whereas women have more ischaemic stroke in the age interval of 55-74 years (57), which could also explain these differences. In this study, ischaemic heart disease was more frequent in men and especially in those in quintile. 1 In contrast, Collier et al. showed that men in quintile 5 had a higher prevalence of ischaemic heart disease (19). Our results are similar to Collier that those men in the last quintile were more likely to be smokers and had more peripheral arteriopathy than men on the first quintile. When we analysed women, those in quintile 5 had a higher prevalence of obesity, hypertension and nearly all complications except for peripheral arteriopathy. Nevertheless, women in quintiles 1 and 2 smoked more than women in the last quintiles. Peripheral arteriopathy was found in the last quintiles by Collier et al. In this sense, smoking could be the cause of this difference.
Strengths and limitations
The main strength of this study was to describe the whole T2D population of Madrid city through real-world data from the EHR. The study was limited by the use of private health of some patients in quintiles 1 and 2, so the record in those quintiles could be less accurate. Additionally, some patients were followed at secondary care facilities, and not all records were available in the primary care EHRs. In our data, we did not have the lifestyle record, treatment of the patients or number of primary care visits; those variables could have helped us to interpret our results more clearly. Lastly, we have missing data from some of the variables which were excluded from the analysis. We provided the number of patients of each group in table 1 but we cannot exclude the possibility of bias because of the missing data.
Implications for practice and research
Our study showed the difficulty in managing T2D as a global disease with multiple targets even among those living in a country with a national public health system. More studies are needed to address T2D as a multitarget disease. Research should be focused in explaining which targets should be prioritized when we are failing to achieve them all. These findings highlight that a minority of patients could achieve all the targets, future studies should explain which factors contribute to reach them and how to take into account those factors in the approach of the disease. But we lighted that sex and SES may have a role in optimal control of diabetes and cardiovascular risk factors. Social determinants, such as the SES index, should be included in the T2D studies and guidelines to improve the quality of care particularly for those who are most disadvantaged. Doctors should be trained to address social determinants as they are trained to treat T2D but also public policies should include take them in account to reduce social inequalities.