Diabetes is a major public health problem worldwide. According to the International Diabetes Federation (IDF) (2017), there were 425 million people aged 20–79 years living with diabetes. Current global estimates indicate that it will increase to 629 million people by 2045 [1]. A systematic review suggests that people with type 2 diabetes mellitus (T2DM) need to focus on adequate self-management and self-care behavior to maintain blood sugar levels to reduce or delay diabetes-related complications [2]. Cumulative average glucose (Hemoglobin A1c: HbA1c) is currently used as the standard for assessing diabetes control. Currently, there is only 23.7 percent among diabetes patients who are treated and well controlled to maintain blood sugar levels [3]. Some reports explain that HbA1c levels greater than 7 percent can significantly increase the likelihood of vascular complications of diabetes [4]. Previous studies have found that factors affecting the incidence of diabetes are physical inactivity, medication use, and stress, which are statistically significantly associated with glycemic control among non-insulin-dependent diabetes mellitus patients [5].

In Thailand, the 6^th Thai Health Examination Survey Report 2019-2020 showed that the prevalence of diabetes as measured by HbA1c among the Thai population was found to be 15 years and over, which increased by 11.0%. In women, the prevalence is higher than in men (12.5 and 9.5%, respectively) [6]. Northern Thailand also continues to see a steady increase in the number of people with diabetes. According to a 2016-2020 report on the number and mortality of chronic non-communicable diseases (NCDs) by the District Health Service, District 1, the mortality rate from diabetes tends to increase approximately 1.8-3.4 times in 10 years [6]. Phayao Province is one of the northern provinces in Thailand with an increasing number of diabetic patients. In 2020, the mortality rate related to diabetes has increased to 18.61 percent of the total population in the province [6].

According to the World Health Organization (WHO), traditional medicine refers to knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures used in the maintenance of health and the prevention, diagnosis, improvement, or treatment of physical and mental illness [7]. Furthermore, it is a belief that it combines plants, animals, and mineral medicines in spiritual healing, preventing illness and maintaining well-being [7]. Herbal medicine (HM) is designated as an essential part of traditional medicine and as the most commonly used complementary and alternative medicine in various parts of the world [8]. Based on a literature review, 80% of people in developing countries rely on traditional medicine as a primary treatment for various ailments [9]. Some reports indicate that herbal medicine is popular, particularly among patients with chronic diseases [10]. Among the practices of traditional medicine, the use of herbal medicines is the most popular and common among the general population and among patients with diabetes [11]. Most traditional medicines are common foods that include vegetables, flowers, fruits, seeds, spices, and herbs. Some foods provide health benefits beyond their nutritional value and are effective in the prevention and treatment of various diseases [12].

According to the Thai Ministry of Public Health’s Department of Thai Traditional and Alternative Medicine, herbs are plants that are part of natural medicine. They have essential ingredients for medicine and are important for humans in daily life [13]. Herbs can be processed into daily food products and health supplements and are also an important ingredient in Thai traditional medicine or pharmaceutical science [13]. The Thai government has a policy to support the use of herbs and Thai traditional medicine from the past to the present. Herbs have been announced to promote health treatment among noncommunicable chronic disease patients, such as diabetes and blood pressure. Herbal medicine is also promoted as an alternative medicine in controlling, preventing, and treating, in parallel with modifying self-care behaviors [14, 15]. A literature review found that developing countries, such as ninety percent of people in Africa and seventy percent of people in India, still rely on traditional medicine and herbal medicine for primary health care to address their health needs [16]. According to a national health interview report in the United States, approximately 40.6 million adults used herbs and supplements in 2012 [17]. Previous studies have identified a number of factors associated with herbal medicinal use, such as gender, education, higher socioeconomic status, and certain health conditions such as myalgia and chronic NCDs [18]. Many people still believe in the traditional way of life, which affects their health and health-seeking behavior. Traditional medicine is used as a main form of primary healthcare and is found in common food ingredients in many countries [12].

There are many ethnic groups residing in northern Thailand. Most of them are located in remote rural areas. Their healthcare is based on the culture and beliefs of the ancestors of each family or community [19]. According to the report, they are also designated as a vulnerable population and suffer from a range of health problems, including NCDs, such as diabetes, hyperlipidemia, and other diseases due to specific lifestyles and dietary cultures [19]. Previous reports have found that herbal-use behavior among rural Thais focuses on primary therapy in the presence of abnormal symptoms and the treatment of chronic conditions [20]. However, there are no studies on herbal-use behavior for health promotion among ethnic groups. Therefore, the purpose of this research was to study the factors affecting herbal-use behavior and glycated hemoglobin (HbA1c) levels in ethnic minorities living at the northern border of Thailand. The findings will be used in the development of appropriate health education programs among ethnic minority groups in accordance with their community contexts, cultures, traditions, and beliefs.

A total of 413 people participated in this study. Females outnumbered males by 56.7% to 43.3%. An average age of the participant was 50.2 years. 56.9 percent of participants obtained a degree in primary education, while 80.1 percent had married, in terms of household income variable, 86.7 percent responded as insufficient revenue. More than half of them (62.5%) had no congenital disease. When the herbs used behavior scores for glycemic control were analyzed by item, item 6: You use herbal medicine to reduce blood sugar levels, had the highest score (mean = 1.98), followed by item 4: You choose herbs that were grown in the house for cooking (mean = 1.96), and item 5: You drink okra tea to reduce blood sugar levels (mean = 1.95). Furthermore, among the behavioral items with low scores for using herbs for self-care was item 2: You use cinnamon herb to reduce blood sugar levels (mean = 1.84), as shown in Table 1.

The results using Pearson’s correlation coefficient analysis showed that health literacy was statistically positively correlated with herbal-use behavior in glycemic control (r = 0.944) and HbA1c. (r = -0.677); while herbal-use behavior in glycemic control was negatively correlated with HbA1c (r = -0.625, p < 0.01). Moreover, the researcher analyzed correlations separately among people with diabetes and without diabetes, as shown in Table 2.

The analysis of the relationship between personal factors and herbal-use behavior in glycemic control revealed that factors including minority groups, age, income sufficiency, occupation, and congenital disease were found to be statistically significantly associated with herbal-use behavior in controlling blood sugar levels at p < 0.05. In the analysis of the relationship between personal factors and HbA1c, it was found that factors including age, income adequacy, occupation, and congenital disease were statistically significantly associated with herbal-use behavior in glycemic control at p < 0.05, as shown in Table 3

Linear regression analysis found that factors including minority groups, age, occupation, and health literacy were statistically significantly associated with herbal-use behavior in glycemic control (R² = 0.902, B = 0.907). Interestingly, the study found that people with underlying diseases (diabetes) were associated with HbA1c levels (R² = 0.479). Finally, factors including age, people with diabetes, and herbal-use behavior in glycemic control were associated with HbA1c levels (R² = 0.423), as shown in Table 4.

Studies have shown that multiple variables are associated with herbal-use behavior in glycemic control; health literacy is especially found to be associated with herb use behavior and the level of HbA1c among ethnic minorities living in northern Thailand. When analyzing herbal-use behavior in controlling blood sugar levels, It was shown that herbal medicine helps reduce blood sugar levels among participants, followed by using herbs grown in the house for cooking. Participants used herbs, including Roselle (Hibiscus sabdariffa Linn) and Betal leaf (Piper sarmentosum Roxb) to lower blood sugar levels (mean = 1.98, 1.96, 1.95, and 1.94, respectively). This is because the properties of Thai herbs help reduce high blood sugar and high blood pressure among people with diabetes [25]. Traditional Thai herbs can be easily obtained locally, especially in households [26]. A previous study explained that Roselle helps control blood sugar levels, especially when eaten fresh and processed in food [27]. Many studies have shown that the properties of betel leaves can help reduce blood sugar and digestion [28]. Previous studies found that local herbs, such as okra, yanang leaves, and stevia, help alleviate the symptoms of illness among patients; these people are aware of the benefits and tend to have health behavior toward herbal use for health care [29]. A study tested rats with high blood sugar injected with herbal extract (Chaplu leaves) mixed with water compared to glibenclamide to reduce blood sugar. The results showed that the blood sugar level of the rats was lower for the first time of the test, and the test ran for seven consecutive days; then, the results showed the same positive results [30]. Similar to studies in the Middle East, 67.3% of participants in Nigeria used herbal medicine for healthcare [8]; North Sudan and Saudi Arabia showed the prevalence of herbal use in T2DM patients at 52% and 25.8%, respectively [31, 32].

When analyzing health literacy, the study found a statistically significant positive correlation with herbal-use behavior in glycemic control. It can be explained through the definition of health literacy, which is defined as individuals’ ability to obtain, process, and comprehend health information and services to make a decision and take action [33]. Additionally, health literacy enhances a person’s ability to access health services and influences self-care decisions. This indicates that individuals with high health literacy result in increased self-care behaviors [34]. Some studies have also revealed that individuals with adequate health literacy are statistically significantly associated with the use of complementary alternative medicine (CAM). Those who use CAM have more access to healthcare providers than those who do not [35]. Studies have also shown that health literacy is a predictor of CAM use among people [36].

When analyzed, the relationship between herbal-use behavior in glycemic control and HbA1c. They were found to be statistically significantly associated. This can be explained by the fact that health literacy enhances. a person’s cognitive skills (thinking, making decisions, and reflecting) to choose the right and most suitable health service for themselves [37]. This is consistent with a study in northeastern Thailand that explained that cognitive skills in health literacy are associated with glycemic control, this essentially means that individuals have access to information and understand health knowledge, leading them to promote their own health [38]. A literature review showed that people with diabetes were 1.6 times more interested in using CAM for glycemic control than drug use for diabetes treatment [39, 40]. Previous studies suggest that more than 1,200 types of herbs have health benefits and efficacy for treatment, which help lower blood sugar and diabetes complications [39]. Consistent with previous studies of people with type 2 diabetes, the majority of participants preferred to use herbs after being diagnosed with DM for their treatment [41]. Furthermore, their results showed that 56.0% of T2DM patients had taken the herbs, and patients felt that their health had improved, no weakness, blood sugar level was lower, and no tingling feeling in the legs [41].

The analysis showed that ethnic groups, age, income, occupation, and underlying diseases were statistically significantly associated with herbal-use behavior in glycemic control. Previous research has shown that biological and sociocultural factors influence individuals’ behaviors toward health practices [42, 43]. Previous studies have indicated that highland ethnic groups have their own food consumption behaviors, which are influenced by their cultures. Indigenous herbs are mainly used in cooking, and there is also a belief that herbs are good for health [44]. Studies in Africa have shown that two-thirds of diabetic patients use alternative therapies, such as herbal medicine, to control their glucose levels and to improve their health [8, 45]. Previous studies focused on household income and health complications of diabetes and showed that they were identified as strong predictors of herbal medicine use [45]. Some studies have found that people with prediabetes, diabetes complications, and a longer duration of diabetes were associated with increased CAM use [31]. Studies have indicated that increased age is associated with an increased choice of alternative medicine among people with diabetes [31, 8]. Interestingly, this study found that age, income, occupation, and underlying diseases were statistically significantly associated with HbA1c. This is consistent with a study that showed that HbA1c was statistically associated with BMI, age, gender, socioeconomic status, education, occupation, and income. An increase in age was also associated with continued increases in HbA1c levels [46].

When adjusted for variables, the study found that health literacy was statistically associated with herbal-use behavior, which had a significant effect on HbA1c levels. According to Pender’s theory, knowledge and cognitive behavior are predictors of a person’s healthcare behavior [43]. A study in Japan found that health literacy was statistically associated with glycemic control [47]. A study in the United States found inadequate health literacy to be a factor associated with poor glycemic control [48]. Aboriginal elderly people with inadequate knowledge and communication skills hinder their access to health information, making them unable to take care of themselves in diabetes control [49]. Some studies have shown that low health literacy results in decreased self-care skills and a greater likelihood of illness leading to hospitalization [50, 51].

There are several limitations to this study. First, the study was a cross-sectional survey; therefore, the researcher was unable to show causal inferences about the associated factors of variables associated with HbA1c. Second, the study participants were ethnic minorities. Therefore, the results of the study cannot be extended to other populations. Third, our herbal-use behavior questionnaire did not specifically identify certain types of herbs; subsequent studies should further identify the types and properties of the herbs and be consistent with their context of ethnic groups. Finally, the participants of this study were a small group and required significant information. Convenience sampling was used, so bias might be included. The results of the research cannot be referenced to other population groups. In the future, qualitative research focusing on the types of herbs and health literacy should be explored in the context of cultural beliefs and traditions.

The study found an association between health literacy and herbal-use behavior, which affects HbA1c levels, among ethnic minority groups in northern Thailand. Therefore, health promotion programs about the use of herbs to help lower blood sugar levels should be organized. Health education programs among ethnic minorities should be focused on increasing health knowledge of the types and properties of herbs and herbal-use behavior to help lower blood sugar levels and understand the health effects and consequences of herbal use. Relevant government and public health agencies should support and promote policies on the use of herbal medicine as alternative healthcare that aligns with ethnic minority people’s cultural context and locality to further reduce diabetes incidence among ethnic minority groups.