Background

Diabetes mellitus is a metabolic disorder associated with many serious medical, psychiatric, familial, occupational, and financial problems [1]. The most serious complications of diabetes include retinopathy, blindness, peripheral neuropathy, foot pain, stroke, heart attack, peripheral vascular disease, vascular disease, and amputation [2]. The global prevalence of diabetes was 9.3% in 2019, equivalent to 463 million people. Predictions for the prevalence of diabetes in 2030 and 2045 are estimated to reach 10.2% and 10.9%, respectively, equaling 578 million and 700 million people. The global prevalence of prediabetes in 2019 was 5.7%, accounting for 345 million people. Predictions for the prevalence of prediabetes in 2030 and 2045 are estimated to reach 8% and 6.8%, respectively, equaling 548 million and 345 million people [1].In a study conducted on the prevalence of diabetes and prediabetes from 2014 to 2020 in 18 geographical regions of Iran among individuals aged 35 to 70, the prevalence rates were 13% and 27% in men and 17% and 24% in women, respectively. The findings of this study indicate that 15% of the adult population in Iran have diabetes, and more than 25% are in the prediabetes stage [3].

Diabetes imposes a significant burden on society, allocating 2.5–15% of healthcare budgets in various countries directly to itself, and when considering the indirect costs, these expenses will be multiplied several times. The burden of diabetes is not merely summarized in financial costs but also includes psychological and social expenses [4]. Studies results indicated that nearly half of patients with type 2 diabetes had insufficient health literacy, and this inadequate literacy imposes significant costs on diabetic patients each year [5,6,7].

Low health literacy is considered a potential barrier to improving health outcomes. Previous studies suggest that low health literacy is consistently associated with poor diabetes knowledge, less self-management behaviors, poor blood glucose control, and costly health care [8].

The World Health Organization has stated that low health literacy is a more widespread issue than some people think; the consequences of this lack of awareness and ignorance by healthcare providers and patients can be detrimental [9].

Afshar Badr et al. conducted a study titled “Developing a Health Literacy Model for Hypertensive Patients”, which showed that the presence of four factors—basic literacy, cognitive literacy, social literacy, and cultural literacy—can influence the health literacy of hypertensive patients [10].

Gowa et al. conducted research on “Sufficiency of Health Literacy and Its Impact on Diabetes Self-Management”. The results showed that health literacy directly correlates with self-monitoring, nutrition and exercise care, diabetes knowledge, self-care, and social support. Overall, health literacy had a direct and significant correlation with self-care parameters in diabetic patients [11]. Jones conducted a study titled “Health Literacy, Self-Management, and Health Outcomes among Adults with Type 2 Diabetes”, which showed that numerical literacy is a vital aspect of health literacy for chronic diseases such as diabetes management [12]. Nayer and colleagues conducted a study titled “Identifying the Level of Health Literacy in Patients with Type 2 Diabetes”. The findings showed that the level of health literacy in patients with diabetes is low, posing a significant challenge to optimizing diabetes care. It is recommended that, in addition to healthcare service strategies, targeted educational and behavioral interventions for the elderly and those with less formal education are essential [13].

By accepting the premise that health literacy can effectively impact health behavior, understanding, and perception of patients, it follows that the health literacy of diabetic patients is also influenced by various factors that need to be discovered and investigated. Health centers and related organizations involved in health must acquire fundamental and comprehensive understanding of the concept of health literacy, as it is a prerequisite for their effective performance in disease control and prevention. Therefore, numerous studies have been conducted to elucidate health literacy, its evaluation methods, and how it can be measured by researchers. However, most of these studies lack the necessary comprehensiveness. Based on this foundation, it is imperative to present a native model tailored to the needs of these centers and aligned with the goals of global health. In this research, we believe that conducting qualitative studies and involving top-tier experts familiar with health and medical matters will transform the concept of health literacy among diabetic patients into a measurable and tangible phenomenon.

Methods

This study, in terms of its applied goal, utilizes mixed data (qualitative-quantitative). The qualitative aspect involves content analysis (conventional approach), while the quantitative dimension employs a cross-sectional survey method. The qualitative research population consisted of 18 experts in health education, medical education, nursing, and educational management with at least a PhD degree, selected using purposive sampling. In order to collect data, a semi-structured interview was used to obtain the participants’ opinions and ideas about health literacy and diabetic patients. Some research questions were: What is the meaning of health literacy training for patients with diabetes? What are the factors that make up the health literacy education model for patients with diabetes? In addition to the questions about health literacy and diabetes, demographic information such as age, gender, years of experience and education level were investigated. Each interview lasted 45 to 75 min. Participants were obtained informed consent.

In the qualitative section, data analysis was conducted simultaneously with data collection. After each individual interview session, the recorded information was listened to at the earliest opportunity. All interviews were transcribed by hand and then typed. The researcher revised the typed material by listening again and comparing handwritten and typed notes to ensure accuracy. The main stages of content analysis were performed with adjustments for coding. MAXQDA version 20 was used for content analysis. The primary codes were extracted and at the end subcategory and category were identified. The accuracy of the data was checked according to Lincoln and Guba criteria [14].

Furthermore, structural equation modeling was utilized in the quantitative section to determine relationships between variables. In the quantitative section, the sample comprised hospital staff from Islamic Azad University of Medical Sciences, Tehran, selected using stratified random sampling with Cochran’s formula, totaling 220 individuals. Data collection tool included a researcher-made questionnaire. This questionnaire was made according to the data of the qualitative section. For this purpose, SPSS version 25 and Smart PLS were employed. “Health Literacy Education” questionnaire has 78 items with Likert rating from “very much” till “very low”. The total score is between 78 and 390. This questionnaire assess 6 dimensions of health literacy education included basic literacy(Questions 1 to 7), specialized literacy(Questions 8 to 34), social literacy(Questions 35 to 42), cultural literacy(Questions 43 to 52), media literacy (Questions 53 to 61) and diabetes management(Questions 62 to 78) (Table 1).

Table 1 Questionnaire “Health Literacy Education” Model • in your opinion, to what extent are the following items used in the field of health literacy education for patients with diabetes?
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In the quantitative section, the sample consisted of 220 participants, including nurses, head nurses, supervisors, and internal medicine, endocrinology, and emergency physicians. These participants were selected from Farhikhtegan, Boali, and Amiralmomenin hospitals, which are under the supervision of the Islamic Azad University of Medical Sciences, Tehran with randomized stratified sampling (See Table 2 for demographic characteristics of the samples).

Table 2 Demographic characteristics of samples of the quantitative section (n = 220)
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The Content validity ratio (CVR) was used for questionnaire validity. Initially, 10 experts were asked to evaluate each item based on a three-part spectrum (essential, useful but not essential, not necessary). The CVR value ranges from − 1 to + 1 according to Lawshe’s Table [15]. An item was considered valid if its CVR value exceeded 0.3 based on the participation of 10 experts, and its reliability was 0.80 according to Cronbach’s alpha coefficient. Also, validity and reliability were calculated and confirmed using the methods of item analysis and confirmatory factor analysis.

For the model design, the main concepts derived from qualitative research were considered, and relevant materials were found through literature review. Then, these findings were organized into a model with 6 dimensions and designed accordingly. In determining the acceptability of the model, two Delphi rounds were conducted using written opinions of stakeholders and questionnaire scores, and necessary changes were made to finalize the model.Regarding the status of each research dimension, t-test was used to examine the opinions of individuals’ averages. A summary of the results of the one-sample t-test based on the average opinions of individuals is presented in Table 3. According to these results, basic literacy with an average of 2.73 had the highest importance (Table 3).

Table 3 Summary of one-sample t-test results for research variables
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The Goodness of Fit (GOF) index is related to the overall fit of structural equation models. It allows the researcher to control the overall fit of their research model after fitting the measurement and structural parts. Trezona et al. [16] introduced values of 0.10, 0.36, and 0.25 as weak, moderate, and strong values for GOF. The results showed that the obtained GOF from the model was above 0.30, indicating an appropriate fit. Finally, using structural equation modeling techniques, the final health literacy model for patients with diabetes in the hospitals affiliated with the Islamic Azad University of Medical Sciences was drawn (Fig. 1).

Fig. 1
figure 1

Conceptual model of health literacy education in patients with diabetes

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Results

Participants in the qualitative section of this study included 8 males and 10 females. Among them, 3 individuals were under the age of 39, 7 were aged between 40 and 45, 6 were aged between 46 and 50, and 2 were over 50 years old. They had work experience ranging from 10 to 30 years. Two participants were professors, 6 were associate professors, and 10 were assistant professors. Findings included six category, seventeen sub category including basic literacy(with sub category of reading and writing, listening, and comprehension), specialist literacy(with sub category of receiving disease-related information, understanding and evaluating disease-related information, decision-making and applying disease-related information, accessing nutritional information, processing nutritional information, decision-making and applying nutritional information), social literacy (with sub category of social interactions and establishing communications for learning), cultural literacy (with sub category of strengthening attitudes and insights, beliefs, and customs), media literacy (with sub category of print media literacy and electronic literacy), and diabetes management (with sub category of self-care behaviors, lifestyle modification, and self-efficacy in diabetes management and control), resulting in 78 items(Table 4).

Table 4 Sub category and category of qualitative section
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Participants in the quantitative section of this study included 61.82% females and 38.18% males. Among them, 21 individuals were aged between 22 and 32, 92 were aged between 33and 42, 82 were aged the age of 39, 7 were aged between 40 and 45, 6 were aged between 46 and 50, 25 were aged over 50 years old. Demographic characteristics of samples show in Table 2.

The average opinion of the respondents about the dimension of basic literacy is 2.73, with t-test 14.15, specialized literacy of 2.51, with t-test 8.08, social literacy of 2.40, with t-test 13.68, cultural literacy of 2.20, with t-test 19, media literacy of 2.21, with t-test 13.87, diabetes management of 2.32, with t-test 15.29, and the significance level of 0.001 confirms the difference between the averages in the current and optimal situation for 6 dimensions (Table 3).

Results were showed the output model of Smart PLS software, presenting a summary of the results related to the standardized factor loadings of the research variables. Path analysis results revealed the direct effect of the basic literacy( β = 0.729,t = 5.729, p < 0.0001), specialist literacy(β = 0.712, t = 5.5.538, p < 0.0001), social literacy (β = 0.630, t = 5.919, p < 0.0001), cultural literacy (β = 0.605, t = 8.509, p < 0.0001), media literacy (β = 0.535,t = 6.401, p < 0.0001)and diabetes management (β = 0.654,t = 7.159, p < 0.0001), on “Health Literacy Education” Model for patients with diabetes was significant (Figs. 2 and 3).

Fig. 2
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Partial least squares pattern (measurement pattern)

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Fig. 3
figure 3

t-value statistics of the research model with the bootstrap technique

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According to the result, the contribution of each factor to the health literacy of patients with diabetes was determined. The results showed that among the dimensions of health literacy in patients with diabetes, the basic literacy dimension with a coefficient of 0.729, the specialist literacy dimension with a coefficient of 0.712, diabetes management with a coefficient of 0.654, social literacy with a coefficient of 0.630, cultural literacy with a coefficient of 0.605, and media literacy with a coefficient of 0.535, respectively, had the highest contribution to the health literacy of patients with diabetes (Table 5).

Table 5 Structural model of health literacy education for patients with diabetes
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Discussion

This research found that the “Health Literacy Education” Model of diabetic patients comprises six dimensions: basic health literacy, specialized health literacy, social health literacy, cultural health literacy, media health literacy, and diabetes management, which is in agreement with the findings of health literacy model of patients with hypertension of Afshar Badr et al. [10]. However, due to the nature of diabetes disease and in order to increase the quality and efficiency of the health literacy model in diabetic patients, in addition to the components of Afshar Badr et al., two components of media literacy and diabetes management have also been added to the model discussed in this research. Also, another difference between the model of this research and the model of Afshar Badr et al. is the use of specialized literacy instead of the cognitive literacy, which has helped to improve the quality of the model of this research. Among these dimensions, the highest coefficient (0.729) pertains to the basic health literacy dimension. Two components were identified for this dimension, with reading and writing receiving the most attention from experts and specialists. Basic health literacy refers to skills and strategies related to reading, speaking, writing, and interpreting numerical figures. In the study by Afshar Badr and colleagues [10], basic health literacy was introduced as an influential factor with components of reading, writing, and knowledge. This concept was consistent with definitions related to basic health literacy. Additionally, this section was aligned with the research of Zeidi and colleagues [17] and Sharbatian and Azarnia [18]. Researchers such as Osborne and Dodson [16], and Sharbatian and Azarnia [18] believed that having literacy in reading and writing is not necessarily effective in the qualitative development of basic literacy and should not be considered as an axis, therefore, it was inconsistent with the results of this research.

For the specialized health literacy dimension with a coefficient of 0.712, six components were identified. Among these, the component of decision-making and the use of disease-related information received the most attention from experts and specialists. This finding is consistent with the results of researchers such as Trezona, Dadson, and Osborne [19], Mohammadi and colleagues [20], Zarcadoolas and colleagues [21], and Tseng and colleagues [8]. Salemi and colleagues [22] and Fadaiyan Arani and colleagues [23] mentioned in their research that the ability to utilize information related to diabetes symptoms and nutritional behaviors constitutes a significant part of specialized health literacy, which aligns with the findings of this study.

For diabetes management with a coefficient of 0.654, the components of self-care behaviors, lifestyle modification, and self-efficacy in diabetes management and control were identified. Ahmadi and colleagues [24] demonstrated in their study that self-efficacy is the strongest predictor of self-care behaviors in patients with diabetes, which is consistent with the findings of this research. The results of studies by Zeidi and colleagues [17] showed that lifestyle modification can contribute to the health of individuals and enhance self-care behaviors. The findings of the present study are in line with the research by Moshavvegh and colleagues [25], Shafiei and colleagues [26] and Macpherson and colleagues [27].

For the social literacy dimension with a coefficient of 0.630, two components were identified: social interactions and establishing connections for learning. Almigbal and colleagues concluded that social literacy is one of the necessary and influential skills for educating patients with diabetes health literacy and emphasized its role in establishing effective communication with others [5]. The findings of this study are consistent with the results of research by Afshar and colleagues [28], AhmadiPour and colleagues [29], and Mogessie [30].

For the cultural literacy dimension with a coefficient of 0.605, components such as enhancing attitudes and insights, beliefs, and customs were identified. A study conducted at Valencia University in Spain titled “Post-Cultural” indicates that in today’s interconnected world, the development and enhancement of cultural literacy is one of the essential tasks of educational institutions [31]. Cultural literacy is an acquirable and teachable ability that translators of any language, regardless of their nationality and culture, can attain through a conscious learning process [32]. This finding is consistent with the studies conducted by AhmadiPour and colleagues [29] and Afshar Badr and colleagues [10]. In Kamali et al.‘s research, it mostly refers to self-efficacy in the management and control of diabetes, and cultural literacy is mentioned as an aid carrier to promote health literacy, which will be inconsistent with this research [33].

For the media literacy dimension with a coefficient of 0.535, the components include print literacy, electronic literacy, and according to the findings of studies by Salemi et al. [22]. , Kamali and Sarafzadeh [33], and Raeisi Nafchi et al. [34], they highlighted that the ability to use virtual spaces related to diabetes plays a significant role in media literacy and ultimately contributes to health literacy.

Limitation and strengths

Since a qualitative approach was used in the first stage of the research, this method has some strengths and weaknesses. Among its strengths are detailed investigation and providing in-depth information on the subject of the research. Another strength of this work is the study of the two dimensions of electronic literacy and the diabetes management that has not been studied in previous researches. But due to the small size of research samples, its generalizability is limited. In the quantitative stage, due to the large volume of items, there was a possibility of the participants’ inaccuracy. Of course, this issue was solved to a large extent by giving enough time to the participants and frequent references of the researcher and emphasizing the importance of accurate answers.

Conclusion

Finally, with the understanding obtained from the dimensions and components and their respective impact, In regard with ”Health Literacy Education” model has a good fitness, it is recommended that this model will be applied in different settings such as hospitals in order to improving the health level of patients. The results can also show planners and policymakers that can be used to all the requirements of diabetic patient education and make proper planning by taking into account all the necessary things for patient education.