Diabetes mellitus (DM) is a chronic condition of high blood sugar in the body. It occurs due to absolute or relative deficiency of insulin or lack of insulin function. Diabetes is a major health issue that has reached alarming levels (IDF, 2021).

The standard diagnostic criteria proposed by International Diabetes Federation and World Health Organization 2021, DM should be diagnosed if one or more of the following criteria are present such as -fasting plasma glucose (FPG) level ≥ 7.0 mmol/L (126mg/dL) or two-hour post prandial glucose after 75g oral glucose load (oral glucose tolerance test (OGTT)) ≥11.1mmol/L (200mg/dL) or HbA1c ≥ 6.5% or random plasma glucose in the presence of symptoms of hyperglycemia  ≥ 11.1mmol/L (200 mg/dL) (IDF, 2021). Diabetes is an epidemic in many developing and developed countries. At present total number of diabetic person globally is nearly 425 million, with a prevalence of 8.8% in the adult population (20 to 79 years), and in Bangladesh it is nearly 7 million, with the prevalence being 8.4% in the adult (20 to 79 years) (BADAS, 2019).

The main causes of the development of diabetes are endocrine disorders that lead to impaired insulin production and secretion, hepatic glucose overproduction, impaired insulin function, or insulin resistance (Mahmoodi et al., 2013). Diabetes is linked with changes in human behavior, sedentary lifestyle, reduced physical activity, and obesity (Shaw et al., 2010). Dietary habit changes and regular physical activities, along with medical care, are routinely used in the DM. In recent years, natural food products have become more popular due to their fewer side effects than medical therapies, and vinegar is one of them (Petsiou et al., 2014). Vinegar has been produced and used in cooking for more than a thousand years. The use of vinegar improves insulin sensitivity, hyperinsulinemia, and hypertriglyceridemia, and can also decrease the random blood sugar (RBS) level in diabetic as well as healthy persons (Mitrou et al., 2015). Today, a common and more popular vinegar is apple cider vinegar (ACV), which has many beneficial effects in the management of endocrine, gastrointestinal, renal, neurological, cardiovascular disorders, and many skin infections (Iman et al., 2015). ACV is a natural vinegar that contains many medicinal components, such as organic acids (acetic, citric, malic, formic, and tartaric), polyphenolic compounds (gallic acid, catechin, ferulic acid). By the process of bacterial fermentation of apple, apple cider vinegar is produced into an acidic solution which contains a number of minerals especially calcium, sodium, potassium, phosphate, etc., vitamins A, B1, B2, B6, C, E, and other trace elements (Budak et al., 2014). Acetic acid is the major component of this cider vinegar, which tends to reduce the possibility of diabetes. The lowering effects of acetic acid on blood glucose level and body weight are based on following mechanisms such as slow gastric emptying, inhibition of disaccharidase activity, activation of the adenosine monophosphate-activated protein kinase (AMPK) pathway, increased insulin secretion, increased postprandial satiety and reduced energy consumption (Launholt et al., 2020). Many studies revealed that regular consumption of this cider vinegar in patients with type 2 DM is associated with improvement of glycemic indices and lipid profile status. The present study is intended to assess the effects of the consumption of ACV in Bangladeshi diabetic patients to improve glycemic status.

Ethical approval of the study protocol

The study protocol was approved by the Research Review Committee and the Ethical Review Committee of Dhaka Medical College, Dhaka.

Study design and setting

This prospective interventional study was conducted in the department of Physiology, Dhaka Medical College, Dhaka, from July 2021 to June 2022. All participants were recruited by purposive sampling.

Inclusion criteria

The inclusion criteria were diagnosed cases of type 2 diabetes mellitus patients according to the International Diabetes Federation and World Health Organization 2021, who were 35 to 60 years old, of both genders, and on the same oral anti-diabetic drug such as Metformin.

Exclusion criteria

Patients on insulin therapy, steroids, oral contraceptive pill, etc, recent or past history of any gastrointestinal, liver, kidney, and heart disease, pregnant or lactating mother, smoking or alcohol intake, and known case of allergy to apple cider vinegar were excluded from the study.

Study procedure

After the selection of the subjects, the nature, purpose, and benefit of the study were explained to everyone in detail. Informed written consent was taken from every subject. They were encouraged to participate voluntarily. They were allowed to withdraw from the study whenever they wanted. The subjects were advised to attend the Department of Physiology, Dhaka Medical College. Each subject was interviewed by a prefixed questionnaire. The questionnaire was prepared regarding personal history, medical history, and drug history. Blood pressure was measured. With aseptic precautions, 6 mL of venous blood was taken at fasting conditions with disposable plastic syringes from each subject. The blood sample was sent for fasting plasma glucose and HbA1c. These parameters were estimated in the Department of Laboratory Medicine, Dhaka Medical College Hospital, Dhaka. These parameters were studied 2 times in the study group and the control group: at the beginning of the study (baseline) and after 12 weeks of the study period. They were instructed not to change their diet, type, and dose of oral anti-glycemic and physical activities during the study. Apple cider vinegar was purchased from the local market. Bragg organic raw unfiltered apple cider vinegar was supplied to the study group in a 473ml bottle with a measuring cup for every 15 days, and patients were encouraged to consume it regularly. All the participants of the study group were instructed to consume 15ml of ACV in 200ml of warm water 1 hour before lunch and dinner for 12 weeks. Regular telephonic contact and periodic visits were made to supply the vinegar and to ensure compliance with the intervention.  After 4 weeks of the study period, 3 patients from the study group were withdrawn from study due to different reasons. Among these 3 patients, two patients showed a lack of interest in taking ACV and one patient had started insulin therapy. So, 32 subjects of the study group and 35 subjects of the control group, a total of 67 subjects, finally completed this study. After 12 weeks, all parameters of both groups were evaluated.

Statistical analysis

Statistical analysis was performed by using a computer-based statistical program, SPSS (Statistical Package for Social Science) version 23. Results were expressed as mean and standard deviation (mean ± SD). p value <0.05 will be considered as the level of significance. Paired Students t-test was performed to compare quantitative data between baseline and after 12 weeks within the group, and the Unpaired Students ʻtʼ was performed to compare quantitative data between study and control groups. The chi-squared test was performed to compare qualitative data between the study and control groups.

A total of 70 diagnosed type 2 DM patients were selected for this study. After 3 dropouts finally 67 diagnosed type 2 patients finally completed the study. 

Table 1: General Characteristics of the patients in the study and control groups (n=67).

Fig. 1: Comparison of sex between the Study and control group (n=67).

Results were expressed as mean ± SD. Unpaired Students test was performed to compare age, and the Chi Square test was performed to compare gender between the study and control groups. 

Table 2: Fasting plasma glucose (FPG) levels in study and control groups (n=67).

The test of significance was calculated, and a p-value < 0.05 was accepted as the level of significance. n = total number of subjects. The mean (±SD) age of the patients in the control group was found to be 44.1±7.46 years, and that of 43.72±7.09 years in study group, and the difference was not statistically significant (p >.05). Similarly, no significant difference was found between genders and control group (p>0.05). 

Table 3: Glycosylated hemoglobin levels in study and control groups (n=67).

Results were expressed as mean ± SD, a = Paired t test was performed for comparison within groups, and b = Unpaired t test was performed to compare between groups. The test of significance was calculated & p <0.05 was accepted as the level of significance. n = total number of subjects, * = significant.

In this present study, the mean fasting plasma glucose (FPG) (p<0.05) was decreased significantly in diabetic patients after consumption of apple cider vinegar in comparison to that of their baseline value but glycosylated hemoglobin (HbA1c) (p>0.05) levels were decreased but no statistically significant association was found in comparison to that of their baseline value. Again, after 12 weeks, mean FPG (p<0.001) and HbA1c (p<0.001) levels were significantly lower in patients with consumption of apple cider vinegar in comparison to that of the control group. Almost similar types of results were observed by different researchers of different countries (Abid et al., 2020; Kausar et al., 2019; Mohammadpourhodi and Sargozaei 2018; Halima et al., 2017). On the contrary, fasting blood glucose was decreased after supplementation with apple vinegar and syrup for five weeks as compared to their baseline value but the level was not statistically significant. A partial explanation for this result could be the short duration of intervention (Heljic et al., 2014). In type 2 diabetes mellitus the inhibitory effects of insulin on gluconeogenesis and glycogenolysis were unopposed and peripheral uptake of glucose was also reduced. All these effects resulted in hyperglycemia which was reflected in increased levels of FPG and HbA1c. Again the type 2 diabetic patients of both groups might have insulin resistance (Akter et al., 2024). The literature review suggested that active ingredients in ACV such as acetic acid and polyphenolic compounds have possible effects on blood glucose such as delayed gastric emptying, suppression of enteral carbohydrate absorption by suppressing disaccharidase, decreased endogenous production of glucose by the liver. The exact mechanism is still unclear. Acetic acid directly activates the AMPK pathways, thus inhibiting gluconeogenesis, and glycogenolysis in the liver (Hlebowicz, 2009; Sakakibara et al., 2006) Facilitation of insulin secretion from β-cell, this results from the fact that vinegar acts by improving the β-cell function (Launholt et al., 2020).

Besides these other mechanisms are reported as – enhanced vasodilation by upregulation of endothelial NOS activity, increased insulin sensitivity of tissues, increased fecal bile excretion, increased postprandial satiety, and reduced energy consumption (Petsiou et al., 2014).

In the present study, after consumption of apple cider vinegar for 12 weeks, fasting plasma glucose and HbA1c were reduced in the study group. Apple cider vinegar might reduce blood glucose by inhibiting gluconeogenesis and glycogenolysis in the liver and increasing the uptake and use of glucose by working muscle. These effects were mediated by the activation of AMPK pathway by acetic acid of ACV. Again through this pathway, NO mediated blood flow to muscle and adipose tissue was increased which results in increased insulin sensitivity of the study group.

In todays world diabetes is one of the burning health issues. Junk and processed food consumption and reduced physical activity are one of the reasons behind it. Natural food product consumption is gaining popularity among the patients of metabolic diseases. ACV has lots of health benefits. After analyzing the results of the study, it can be concluded that regular consumption of apple cider vinegar can improve glycemic status in patients with type 2 DM. Therefore, apple cider vinegar may be helpful to minimize the complications of type 2 DM. We recommend the assessment of HOMA-IR and level of oxidative stress to confirm the mechanism of action of the ACV to improve insulin sensitivity and reduce insulin resistance.

K.F.: Conceptualization, methodology, and writing the manuscript. D.B.; F.H.; S.H.; and T.I.T.: Contributed to data analysis, investigation, visualization, and supervision. T.M.; U.S.; S.F.; S.A.A.: Finally checked the manuscript and editing, data curation, funding acquisition, and formal analysis. All authors who are involved in this research read and approved the manuscript for publication.

The authors are thankful to the study subjects for their active, sincere, and voluntary participation.

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