Diabetes mellitus is a metabolic disorder characterised by hyperglycaemia resulting from the absence, inadequate production or deficiency of the hormone insulin or functional resistance to its action.¹ The long-term persistence of these physiological abnormalities contributes to vascular morbidities and progressive functional deterioration.^2,3 Globally, an estimated 589 million individuals are currently living with one of the different types of diabetes, with projections suggesting an increase to 853 million by 2050.⁴ The most significant relative increase is anticipated to occur in low- and middle-income countries, which already account for the majority (81%) of diabetic cases.⁴ In South Africa, the burden is substantial, with 400 000 new diagnoses among adults 20–79 years between 2011 and 2024, of which 90% were type 2 diabetes mellitus (T2DM).^4,5 The Eastern Cape province, particularly rural districts such as OR Tambo, has witnessed a marked increase in both prevalence and incidence of type 2 diabetes.^6,7

The rising prevalence of diabetes in South Africa reflects both avoidable and unavoidable determinants. These include changing population demographics associated with increased life expectancy, facilitated by improved healthcare access and successful antiretroviral therapy^8,9,10,11,12, familial predisposition^12,13, rural-urban migration, which is often accompanied by the adoption of sedentary lifestyles and an unhealthy diet^7,14,15, and escalating rates of obesity and psychological distress.^12,16,17 Evidence indicates that individuals with T2DM often develop additional risk factors encompassed within metabolic syndrome,^18,19,20 a condition defined by the co-occurrence of insulin resistance, obesity, atherogenic dyslipidaemia and hypertension.^21,22 These interrelated abnormalities share common mediators, mechanisms and pathways,²³ and their cumulative effect causes microvascular dysfunction, amplifies insulin resistance and exacerbates hypertension.²⁴

Globally, metabolic syndrome is increasingly prevalent, affecting 20% to 25% of the general adult population and 70% to 80% of individuals with T2DM.²⁵ In sub-Saharan Africa, prevalence estimates among T2DM patients vary depending on diagnostic criteria, ranging from 60.8% with the International Diabetes Federation (IDF) to 63.1% with the National Cholesterol Education Program-Adult Treatment Panel (NCEP-ATP) III 2004.²⁵ Country-specific studies also demonstrate considerable heterogeneity: in the Gwalior Chambal region of central India, prevalence rates were 28% with WHO definitions, 45.8% with IDF and 57.7% with NCEP-ATPIII;²⁶ in Ghana, prevalence was 58% using NCEP-ATPIII²⁷ and 59.90% using harmonised criteria;²⁸ while rates of 52.38% in Ethiopia,²⁹ 63.6% in Nigeria³⁰ and 80.5% in Nepal³¹ have also been reported. Importantly, individuals with metabolic syndrome are at substantially greater risk of myocardial infarction and other cardiovascular diseases, particularly when coexisting with T2DM.²⁵ Although a bidirectional relationship exists between metabolic syndrome and T2DM, with each increasing the likelihood of the other, not all patients with one condition necessarily develop the other. Risk factors include demographic variables such as gender and body mass index (BMI),^27,28,29 lifestyle factors such as physical inactivity,³² clinical factors including elevated blood pressure and elevated triglycerides³² and genetic predisposition to diabetes.²⁸ In developing countries, lifestyle-related risk factors predominate, compounded by demographic and Western lifestyle influences.³³

Despite the growing burden, uncertainty persists regarding the prevalence and predictors of metabolic syndrome in a typical South African population, as context-specific evidence remains limited. Accordingly, the present study was undertaken to determine the prevalence, components and predictors of metabolic syndrome among type 2 diabetic patients attending a rural tertiary hospital in the Eastern Cape. By identifying individuals at heightened risk of severe metabolic crisis and macrovascular and microvascular events,^34,35 the study is expected to furnish robust evidence to support routine screening, integrated multimorbidity management and epidemiological investigations aimed at identifying root causes in clinical settings.

Metabolic syndrome encompasses multiple risk factors arising from insulin resistance, accompanied by abnormal adipose tissue deposition and function.²⁴ Patients with metabolic syndrome have a twofold increased risk of cardiovascular disease within 5 years to 10 years and a fivefold increased risk for T2DM.³⁷ Low- and middle-income countries already bear a disproportionate burden of T2DM (4 in 5 persons) compared to the global ratio of 1 in 9.⁴ By 2050, diabetes prevalence is projected to rise by 45% globally, with increases of 10% in Europe (72.4 million) and 142% in Africa (59.5 million).⁴ In general, metabolic health rates show no evidence of decline across high-, middle- and low-income countries³⁸; with disproportionately elevated prevalence observed among ageing, urbanised, non-African females and high-income level populations.^38,39 Pooled analyses estimate a global prevalence of 31.4% and higher rates in high-income countries (33.4% – 34.6%) compared to Africa (23.1%).³⁹ Among individuals with type 2 diabetes, prevalence is elevated in high-income countries such as Spain⁴⁰ and reaches 63.1% in sub-Saharan African countries,⁴¹ with Southern African countries most affected.⁴²

Metabolic syndrome is increasingly prevalent worldwide, primarily driven by rising obesity and sedentary lifestyles. Consequently, it represents both a public health challenge and a clinical issue. At the population level, a greater emphasis is required on lifestyle changes to reduce obesity and promote physical activity. At the clinical level, early identification of individuals affected is essential to mitigate multiple risk factors.³⁷ In South Africa, literature on the prevalence and predictors of metabolic syndrome remains limited, with no prior studies conducted among patients with T2DM in Mthatha, Eastern Cape.

In the present study, metabolic syndrome was identified in 83.8% of participants, exceeding prevalence estimates reported among type 2 diabetes patients in Ethiopia (52.38%), Nigeria (63.6%)^29,30 and Ghana (58%) using the NCEP-ATPIII and 59.90% using the harmonised criteria.^27,28 A systematic review of sub-Saharan African populations reported prevalence estimates of 60.8% by IDF criteria and 63.1% by NCEP-ATPIII.²⁵ Thus, the prevalence observed in the present setting falls within the reported range for sub-Saharan Africa but is notably higher. Comparable rates have been documented in Asia, with Nepal reporting 80.5%³¹ and central India 57.7%.²⁶

Among the 119 individuals with metabolic syndrome, prevalence was higher among females (90.3%) than males (66.7%). Comparable findings have been reported in Ghana, where the prevalence in females was approximately threefold that of males (77.01% vs. 22.99%),²⁷ and in Ethiopia, where females also exhibited higher rates.²⁹ A systematic review across sub-Saharan Africa similarly demonstrated a pooled prevalence of 71.6% (95% CI: 60.2–82.9) in females compared to 44.5% (95% CI: 34.2–54.8) in males.²⁵ In Asia, prevalence was higher among females in both central India (58.1% vs. 41%)²⁶ and Nepal.³¹ Notably, the gender-stratified prevalence observed in the present study exceeds that reported in these settings. In contrast, findings from North Central Nigeria indicated a higher prevalence in males (74.5% vs. 64.9%; p < 0.05), attributed to the greater physical activity among women in that region.³⁰

The higher prevalence of metabolic syndrome among females in the present study may be attributed to differences in health-seeking behaviour, as women are more likely than men to consult a healthcare practitioner at the early disease stages.⁴³ In South Africa, particularly among the black population, females generally have higher body weight than males,⁴⁴ which may reflect a combination of genetic predisposition and the influence of Western dietary patterns.⁴⁵ Furthermore, weight gained following multiple pregnancies often proves challenging to reverse.⁴⁶ Given that females comprised 72.5% of the study population, they contributed substantially to the overall obesity rate of 63.4%. The greater proportion of males in the non-metabolic group may be explained by the use of European-derived waist circumference cut-offs, which may be set too high for African males (≥ 94 cm) and too low for South African black females (≥ 80 cm) who are typically more obese.⁴⁷

In the present study, increased waist circumference (indicative of abdominal obesity) was the most prevalent component, observed in 90.8% (n = 129) of participants. This was followed by low HDL-C (86.1%), dyslipidaemia (82.4%), hypertriglyceridaemia (81.7%), hypertension (78.1%) and obesity (63.4%). Comparative data from North Central Nigeria reported central obesity in 80% of patients, hypertension in 63%, hypertriglyceridaemia in 62% and low HDL-C in 70%,³⁰ all lower than the rates observed in the present setting. A systematic review of metabolic syndrome components in sub-Saharan Africa, based on IDF criteria, documented pooled prevalence rates of central obesity (61.6%), low HDL-C (49.9%) hypertriglyceridaemia (49.2%) and hypertension (56.1%).²⁵ In Nepal, central obesity (↑waist circumference) was the most prevalent component (99.9%), higher than the rate in the present study.³¹ Similarly, an Indian study using NCEP-ATP criteria reported increased waist circumference in 64% of participants, with a lower prevalence of hypertension (45%), hypertriglyceridaemia (46%) and low HDL-C (30%), compared with the present findings. In Ghana, using NCEP-ATP III criteria, hypertension was the predominant component (60%), followed by high waist circumference,²⁷ which contrasts with the present study and other reports, where increased waist circumference was most common.

In developing countries, increasing urbanisation and lifestyle changes have led to a greater adoption of Western dietary patterns, characterised by refined carbohydrates, processed foods and unhealthy fats.^48,49 This trend has contributed to the rising prevalence of obesity and dyslipidaemia,⁵⁰ which may explain the high rate of dyslipidaemia (82.4%) in the present study. Hypertension is also increasing in these countries, likely because of factors such as inadequate sleep from demanding work schedules, insufficient physical activity and financial stress.⁵¹ Accordingly, the high prevalence of hypertension (78.1%) in this population was not unexpected. Furthermore, a substantial proportion of participants had an HbA1c level greater than 7%, indicating poor glycaemic control among both the metabolic and non-metabolic groups. This may be attributed to limited financial resources, restricting patients’ ability to attend regular clinical reviews or access treatment. Individuals from low socioeconomic backgrounds also face challenges in adhering to dietary recommendations, as financial constraints hinder their ability to purchase appropriate food.⁵²

Among the study participants who met the IDF criteria for metabolic syndrome (83.8%), the prevalence of individual components was as follows: hypertension (82.9%), dyslipidaemia (88.6%), low HDL (90.5%) and hypertriglyceridaemia (88.1%). Obesity was present in 69.7% cases. No statistically significant gender differences were observed for these variables. This finding contrasts with results from Ghana, where central obesity and low HDL levels differed significantly between males and females under the NCEP-ATPIII criteria.²⁷ In North Central Nigeria, 79% of metabolic syndrome subjects had dyslipidaemia, and 41% were obese (↑BMI),³⁰ indicating a lower dyslipidaemia rate compared with the present setting (88.6%). Similarly, data from central India reported hypertension (69%), high triglyceride (44%) and low HDL (59%) among metabolic syndrome subjects,²⁶ all of which were lower than the rates observed in the cohort for the present study.

In the non-metabolic syndrome group, males predominated (56.5%) compared to females (43.5%), whereas the metabolic syndrome group showed a higher proportion of females (56.5%). Significant differences were observed between the metabolic and non-metabolic syndrome groups with respect to gender, obesity (92.2% vs. 7.8%), hypertension (90.7% vs. 9.3%), dyslipidaemia (93.5% vs. 6.5%), hypertriglycerides (93.2% vs. 6.8%) and low HDL-C (90.5% vs. 9.5%). These findings are consistent with the established association of metabolic syndrome with female gender, obesity and increased waist circumference. Comparable results were reported in India, where significant differences between metabolic syndrome and non-metabolic syndrome groups were noted for age, gender, weight, BMI, waist circumference (WC), systolic and diastolic blood pressure, TG and HDL-C.³²

In the present study, binary logistic regression analysis of gender, BMI, blood pressure and dyslipidaemia identified female gender, hypertension and dyslipidaemia as independent predictors of metabolic syndrome. Given the predominance of females in the cohort, gender subgroup analysis was performed. Obesity emerged as the independent factor associated with metabolic syndrome in males, whereas dyslipidaemia was the independent factor in females. Similar findings have been reported elsewhere: in Ethiopia, female gender and BMI were associated with metabolic syndrome among patients with T2DM.²⁹ In Ghana, gender, BMI and educational status were identified as risk factors when NCEP-ATPIII criteria were applied.²⁷ In India, elevated TG, diastolic blood pressure, WC, sedentary behaviour (h/day) and lack of moderate activity (≥ 150 min/week) were significantly associated with metabolic syndrome among diabetes patients (p < 0.05).³² In the present cohort, obesity was confirmed as an independent risk factor in males, reflecting increased WC alongside other components of metabolic syndrome. However, evaluation of factors associated with hypertension and dyslipidaemia did not yield significant associations, particularly with respect to age and hypertension. This is notable, as hypertension typically increases with age, making the absence of such an association unexpected.⁵³

The identification of established components of metabolic syndrome as risk factors demonstrates their magnitude and independent contribution to the overall risk. Dyslipidaemia was confirmed as the principal driver among females. At the same time, obesity was the key determinant among males in this rural South African cohort, highlighting the relevance of gender-specific prevention strategies. The high prevalence of metabolic syndrome observed has important clinical implications. Firstly, adults with type 2 diabetes, especially women with dyslipidaemia and obese men, should be routinely screened for metabolic syndrome during outpatient visits to enable early intervention and reduce morbidity and mortality burdens for both patients and the healthcare system. Secondly, a systematic assessment to exclude metabolic syndrome in individuals with dyslipidaemia or high BMI should be integrated into the multimorbidity management models. Thirdly, multifactorial cardiovascular disease risk management should be reinforced in type 2 diabetes cohorts with metabolic syndrome.

This study demonstrated a high prevalence of metabolic syndrome among T2DM patients managed at Nelson Mandela Academic Hospital in Mthatha, consistent with studies conducted both within and outside Africa. Metabolic syndrome was more prevalent among females, with abdominal obesity identified as the main risk component. Dyslipidaemia and obesity were independent factors associated with metabolic syndrome.