Prevalence, Characteristics and Potential Risk Factors of Prediabetes in Primary Health Care: A Cross-Sectional Study

Introduction

Diabetes is a group of metabolic diseases and a serious, long-term (chronic) condition which characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both.^1–3 Based on the 10th edition of the International Diabetic Federation (IDF) Atlas, the prevalence of diabetes is estimated to be 537 million adults aged 20–79 years worldwide (10.5%). This includes both type 1 and type 2 diabetes as well as diagnosed and undiagnosed diabetes. The adult population with diabetes aged between 20-79 years is estimated to be 19,465,100 in Indonesia. Instead, the prevalence of diabetes among the ages–20-79 years is 10.6% (of the total adult population aged 20-79 years is 179,720,500). In other words, one in nine people in Indonesia had diabetes.² T2DM is one of the most important causes of morbidity and mortality worldwide.⁴

Prediabetes is a condition that results in high BGL and often leads to T2DM.⁵ People with prediabetes have high BGL (are below the amount needed to be diagnosed with diabetes, but they are at a higher risk of getting diabetes.⁶ According to the World Health Organization (WHO), prediabetes is an intermediate level of high blood sugar. They use two specific tests to define it: impaired FBGL, which means BGL of 6.1 to 6.9 mmol/L (110–125 mg/dL) before a meal, or impaired OGTT, which mean OGTT of 7.8 to 11.0 mmol/L (140–199 mg/dL) two hours after eating 75 g of oral glucose.⁷

According to the American Diabetes Association (ADA), the criterion for identifying impaired FBGL between 5.6 and 6.9 mmol/L (100-125 mg/dL), impaired OGTT between 7.8 and 11.0 mmol/L (140-199 mg/dL), and HbA1c levels between 5.7% and 6.4% (39-47 mmol/mol).^8,9 Both definitions rely on FBGL measurements, 2-hour plasma glucose concentrations during an OGTT, and HbA1c concentrations.¹⁰ In Indonesia, the diagnostic criteria for prediabetes align with those established by the ADA.¹¹ The significance of Impaired FBGL and impaired 2-hour postprandial OGTT is threefold: they signal an elevated chance of developing T2DM in the future, indicative of an existing heightened risk of cardiovascular disease (CVD), and identifying therapies that can prevent the onset of T2DM.²

Individuals with Impaired FBGL and impaired OGTT are at a high risk of developing T2DM, with up to 50% within five years.^8,9 Untreated T2DM for a prolonged time can lead to complications such as retinopathy, neuropathy, CVD, or stroke.^12–14 These chronic implications contribute to diabetes distress and health expenditures.^15,16 Diabetes distress is a hidden emotional burden in DM.¹⁷ Healthcare expenditure for people with diabetes is expected to reach 1,054 billion USD by 2045.¹⁸ The cost of managing individuals with T2DM and complications is two times higher than that for individuals without complications.^19,20

Risk factors for prediabetes include BMI, waist circumference, ethnicity, family history, and sex.^2,9,21 Other risk factors include hypertension, low levels of HDL cholesterol, smoking, and low levels of education and income.²² According to the RISKESDAS (National Basic Health Research) Indonesia, the increase in diabetes data is in line with the rise in obesity rates, a risk factor for diabetes, from 14.8% to 21.8% in 2013-2018. In addition, it is also in line with the increase in BMI from 11.5% to 13.6% and central obesity from 26.6% to 31%.^23,24 Intensive lifestyle and pharmacological intervention can significantly reduce the risk of progression to diabetes in patients with impaired FBGL or impaired OGTT.^25,26

Medan was chosen as the study location due to its notably high burden of diabetes, which reflects a growing concern in the region. According to the Medan City Health Office (2012), diabetes was the second most common non-communicable disease after hypertension, with 10,347 diabetes patients recorded across 39 primary health care centers. This number has continued to rise, highlighting the urgent need for early detection and prevention strategies. Furthermore, data from the Indonesian Ministry of Health (2018) reported a national diabetes prevalence of 8.5%, or approximately 20.4 million individuals, while Riskesdas (2023) data revealed that North Sumatera’s prevalence was 8.47%, indicating a sustained public health issue. Globally, the International Diabetes Federation estimated that 537 million adults had diabetes in 2021, with Indonesia ranking 7th among countries with the highest number of cases.²⁷ Given this context, investigating prediabetes in Medan is crucial not only due to the rising local trend but also to support resource allocation by local health authorities and to inform targeted interventions at the primary care level. This study aimed to investigate the prevalence, characteristics, and potential risk factors for prediabetes in primary health care in Medan, Indonesia.

Methods

Results

Discussion

Our study demonstrated that the prevalence of individuals with prediabetes in Medan, Indonesia, using HbA1c, FBGL, and 2-hours postprandial OGTT were 28.1%, 50.6%, and 28.1%, respectively. The prevalence of prediabetes based on FBGL examinations in 33 provinces in Indonesia was 10%.³¹ In this study, the prevalence of prediabetes using FBGL was one-fifth of that in the previous study. Another study found that the prevalence of prediabetes in Pontianak with an FBGL > 100 mg/dL was 76.5%. A significant increase in the prevalence of prediabetes has also been reported in the US, Europe, North America, the Caribbean, Africa, West Iran, and Malaysia.^32,33 The global prevalence of prediabetes using FBGL and 2-hours postprandial OGTT is estimated to increase to 6.5% and 10%, respectively, in 2045.⁸

The American Diabetes Association (ADA) defines impaired fasting glucose (IFG) as having a fasting plasma glucose (FPG) level of 100–125 mg/dL, impaired glucose tolerance (IGT) as having a 2-hour postprandial glucose of 140–199 mg/dL, or elevated HbA1c (5.7%–6.4%) as having “prediabetes,” or intermediate hyperglycemia, and advises this population to make preventative efforts.⁹

In this study, we found that most patients with prediabetes were 55-64 years old (n=69, 39.1%), but the prevalence was higher among age >64 years (n=11, 91.7%). In this study, we also found that age >64 years was significantly associated with the incidence of prediabetes (p=0.001, 95% CI; 1.515-4.628) based on chi square test, and was a risk factor of prediabetes (p=0.0001, 95% CI; 1.787-5.481) based on poisson regression test. Respondents aged >64 years were 3.13 times more at risk of experiencing prediabetes. Similar to the study by Andriani et al., the majority of prediabetic patients were >50 years old. A previous study also found a significant relationship between age and incidence of prediabetes (p=0.029).²² Numerous additional factors that may impact the etiology of prediabetes are also associated with advanced age. Peripheral insulin resistance is increasing in tandem with these processes. with a poor diet, little exercise, or obesity. Hyperglycemia results if this process occurs in people who are at risk of developing prediabetes. The degree of environmental exposure and lifestyle choices have a significant impact on the rate and timing of development.²²

In this study, we found that 82% of the respondents were female and the most patients with prediabetes were female (n=26, 35.6%). Female was significantly associated with the incidence of prediabetes (p=0.001, 95% CI; 0.297-4.0.646) based on Chi square test, and was a risk factor of prediabetes (p=0.0001, 95% CI; 0.244-0.669) based on poisson regression test. Female was 0.4 times more at risk of experiencing prediabetes. This study is consistent with research conducted in Pontianak, showing that female are more prevalent among people with prediabetes.²² Women of reproductive age are less susceptible to cardiovascular disease because of the protective effects of estrogen. Estrogen commonly reduces triglyceride and LDL-C circulating levels, while increasing HDL-C levels. However, some studies have mentioned the development of cardiovascular disease in women with lower blood glucose levels than in men.^34–37

The prevalence of physical inactivity in the subjects diagnosed with prediabetes in this study was 56.4%. It was significantly associated with the incidence of prediabetes (p=0.034, 95% CI; 1.032-4.2.667) based on chi square test, and was a risk factor of prediabetes (p=0.005, 95% CI; 1.227-3.096) based on poisson regression test. Peoples that never do daily exercise were 1.94 times more at risk of experiencing prediabetes. This is inline with previous research which states that a sedentary lifestyle influences the development of prediabetes and diabetes. Exercise helps to avoid obesity and increases insulin sensitivity. Compared to people who exercise, those who do not exercise may be more susceptible to developing prediabetes and diabetes,³⁸ and physical activity is known to be protective against the onset of type 2 diabetes.³⁹ Program-intensive lifestyle interventions from the DPP were to achieve and maintain a minimum weight loss of 7% and a physical activity of 150 min per week identical in intensity to brisk walking. The goal of physical activity was to approximate at least 700 kcal/week of physical activity.⁴⁰

The prevalence of prediabetes among groups who do not consume vegetables/fruits every day is higher (44.2%), compared to those who consume vegetables/fruits every day (43.5%). But, we did not find an association between consuming vegetables/fruits every day and prediabetes. Consuming fruits and vegetables has been linked to the prevention of a number of chronic conditions, such as diabetes and prediabetes. These benefits have been attributed to the high nutrient content and low energy of fruits and vegetables. Fruit consumption up to 200 g/day was associated with a lower relative risk of type 2 diabetes; intakes beyond this threshold were associated with an increased risk of diabetes, possibly due to the increased intake of fructose from fruit, which has been associated with a reduction in insulin sensitivity. On the other hand, results from future research have been mixed. In one study, fruit and vegetable intake was compared to prediabetes risk in 150 prediabetes cases and 150 controls. The results showed an inverse relationship. There could be a connection between these discrepancies and the nutritional evaluation technique that was employed.⁴¹ The 12-week intervention consisted of four nutrition visits and instructions on a high-carbohydrate diet (60% to 70% daily calories), high-fiber diet, and low-fat diet (<7% calories from saturated fat). The results showed 5% weight loss.⁴² In a study of participants at a high risk of diabetes, dietary fiber intake lowered postprandial blood glucose and insulin resistance. The recommended dietary fibre intake recommendation is 3.0 g or 1,000 kcal of total energy per day to prevent T2DM.¹⁶

The pravelence of obesity based on BMI and waist-hip circumference ratio in the subjects diagnosed with prediabetes in this study was 45.7% and 40.9%, respectively. The prevalence of obesity based on BMI was higher than normoweight subjects, but the prevalence of obesity based on waist-hip circumference ratio was lower than normoweight subject.

While BMI is widely used for general adiposity assessment, we recognize its limitations in distinguishing between fat and lean mass. BMI poses bigger bias than waist circumference and waist-hip ratio despite its practicability. In this study, we discuss BMI cautiously and acknowledge that central obesity measures such as waist circumference or WHR may better reflect cardiometabolic risk, especially in Asian populations who are more prone to visceral fat accumulation. However, in this study, we did not find an association between BMI, waist-hip circumference ratio and prediabetes. This study is consistent with research conducted in Pontianak, showing that overweight or obesity are more prevalent among people with prediabetes.²² BMI is a simple anthropometric measure commonly used to measure general adiposity.⁴³ Asian populations have more visceral fat than Caucasian populations do. This results in metabolic disorders, lipotoxicity, and insulin resistance. In addition, limited insulin secretory capacity and genetic predisposition play important roles in the development of insulin resistance. Several studies have reported that there is no relationship between BMI and the obesity paradox, and BMI acts as a simple indicator for evaluating the risk of blood glucose and lipid metabolism.⁴² Maintaining a normal weight BMI is essential in the education of patients with prediabetes and is a concern for physicians.⁴³

Our study found that low HDL (<60 mg/dl), high LDL (≥100 mg/dl), high trygliceride (≥150 mg/dl), and high total cholesterol (≥200 mg/dl) were more frequent among prediabetes patients. Among all of lipid profiles, high trygliceride (≥150 mg/dl) was significantly associated with the incidence of prediabetes (p=0.004, 95% CI; 1.250-3.135) based on chi square test. This is consistent with a study by Li et al. from 2024, which also revealed that, after controlling for confounding variables, standard lipid measures showed trygliceride to be an independent risk factor for prediabetes, while HDL and LDL seemed to be possibly protective. There is evidence that a common dyslipidemia feature in prediabetic patients is hypertriglyceridemia. Increased free fatty acids from elevated trygliceride levels stimulate changes in pancreatic α cell insulin signaling and excessive glucagon release, which ultimately culminates in insulin resistance. On the other hand, insulin resistance increases trygliceride levels by blocking trygliceride lipolysis, which raises free fatty acids in the liver and lowers HDL by lowering the expression of apolipoprotein A-I, which is required for HDL synthesis. The “vicious circle” of diabetes development is aided by the causal link that exists between trygliceride and insulin resistance. Out of all the conventional lipid measures, trygliceride was found to be the most significant factor linked to prediabetes in the current investigation.⁴⁴

Triglyceride levels are known to be the most variable lipid parameter and are highly sensitive to fasting duration. While our participants fasted for approximately 8–10 hours, which is slightly below the recommended 12–14 hours for triglyceride stability, interpretation was made with caution. As supported by Nordestgaard et al. (2018)​, non-fasting lipid profiles can still be valid in large-scale screenings, especially when analytical consistency and interpretation guidelines are applied.⁴² However, from the results of the multivariate analysis, none of the lipid profiles were risk factors for prediabetes in this study.⁴⁴

In this study, we found that high blood pressure was more frequent among prediabetes patients. High diastolic blood pressure (≥90 mmHg) was a risk factor of prediabetes (p=0.014, 95% CI; 1.125-2.897) based on poisson regression test. Peoples with high diastolic blood pressure (≥90 mmHg) were 1.8 times more at risk of experiencing prediabetes.

This is consistent with a study by Huang et al. from 2020, which also stated that, one of the most prevalent chronic illnesses, hypertension, is a significant modifiable risk factor for metabolic and cardiovascular disorders, including prediabetes and diabetes. In populations with a reduced risk of cardiovascular disease, hypertension was linked to a higher risk of mortality. When prediabetes was added, this risk increased even further.⁴⁵ In this study, we also found that the prevalence of prediabetes was higher among groups who have achantosis nigricans (100%). But, it was not statistically significant (p=0.105), possibly due to the small number of cases. This contradict the claim that achantosis nigricans was found to be associated with insulin resistance. Achantosis nigricans is a dermatosis that usually affects the neck and intertriginous surfaces. Acanthosis nigricans is a clinical marker of insulin resistance and has been found to correlate with prediabetes and T2DM risk. It is characterized by velvety, papillomatous, brownish-black, hyperkeratotic plaques.⁴⁶ Additionally, this study also contradicts a 2020 study by Alvarez that found people with normoglycemia, prediabetes, and type 2 diabetes had significant (>85%) achantosis nigricans specificity and positive predictive value. Achantosis nigricans’s positive predictive value for insulin resistance were high across nearly all categories of carbohydrate tolerance. This implies that in those who are euglycemic or have prediabetes, achantosis nigricans is a reliable and early clinical indicator of insulin resistance.⁴⁷

In this study, of 13 risk factors, only 4 risk factors have significant correlation with prediabetes in Medan (p<0.05), namely age >64 years, female, never doing daily exercise, and diastolic blood pressure ≥90 mmHg. Preventing type 2 diabetes mellitus provides significant public health benefits, including lower rates of complications.⁴² Implementing lifestyle counselling in clinical practice is feasible and cost-effective.³³ Holistic and integrated coordination is needed to assess the disease, including early detection in high-risk factor populations, targeted treatment, and intensive lifestyle modification.

This study has several limitations. The sample size was relatively small and drawn from a single health center, which may affect generalizability. The use of a non-randomized sampling method could introduce selection bias. Additionally, the cross-sectional design limits the ability to infer causality. However, we minimized bias by using standardized measurement tools, trained examiners, and validated laboratory methods. Future studies with larger, multi-site samples and longitudinal follow-up are recommended to confirm and expand these findings.

Conclusion

This study found that the prevalence of prediabetes based on HbA1c, FBGL and 2-hours OGTT levels was 28.1%, 50.6%, and 28.1%, respectively in Medan. Age >64 years, female, physical inactivity, and diastolic blood pressure ≥90 mmHg were the most important risk factors for prediabetes. Early detection is necessary to assess high-risk factors, targeted treatment, and intensive lifestyle modifications.