European Journal of Cardiovascular Medicine

Diabetes mellitus (DM) continues to assume pandemic proportions, affecting people across various socioeconomic groups in developed and developing nations. Globally, close to a half billion people are living with diabetes and it is expected to increase by more than 50% in the next 25 years [1]. The complications are mainly vascular and lead to diabetes-specific micro vascular sequelae in the retina, nerves and the glomerulus. Others are atherosclerotic macrovascular pathology in the brain, heart and lower limbs [2].

Lower extremity complications are common, showing a rising trend in many regions of the world and affecting about 131 million people worldwide, with an estimated global prevalence of 1.8% [3]. Although much emphasis has been laid on neuropathy as a cause, an equally important contributor to the occurrence of leg ulcers and amputations is peripheral arterial disease (PAD) [2,4-6]. Consequently, PAD is under-diagnosed and hence, may be undertreated.

Peripheral artery disease (PAD) is defined as atherosclerotic occlusive disease of lower extremities, In DM, the arteries of the lower limbs are the ones that are mostly involved; and most often the distal arteries,

especially the dorsalis pedis artery [7]. PAD increases risk of lower extremity amputation and is also a marker for atherothrombosis in cardiovascular, cerebrovascular and renovascular beds. Patients with PAD therefore have an increased risk of MI, stroke and death [8]

The ABI is a sensitive and specific screening tool for PAD. It has a sensitivity of 90% and specificity of 98% in detecting PAD [10]. An ABI of < 0.9 is indicative of PAD, and is associated with a 2- to 4 -fold increase in mortality . An ABI of > 1.3 is indicative of poorly compressible vessels resulting from vascular calcification[11].

Pulse oximetry measures peripheral blood hemoglobin oxygen saturation. Low blood flow in an extremity produces lower oxygen saturation in the blood. It’s a safe, non-invasive and instantaneous measurement of blood oxygenation without need for any special training. Studies have found that pulse oximetry of the toes was comparable to ABI in screening for lower extremity arterial disease [14-19]. 

Only a few studies have assessed ABI and pulse oximeter as a screening tool for asymptomatic PVD in diabetic patients in India and hence the need for this study. [21,22] This vindicates the need for our study which aims to compare pulse oximetry with Ankle brachial index and test its power as an independent tool in early detection of PAD in DM patients.

AIM AND OBJECTIVES

• To assess the usefulness of Pulse oximetry in detecting Peripheral Vascular   Disease in asymptomatic patients with diabetes mellitus.
• To assess the usefulness of Ankle Brachial Index in detecting Peripheral Vascular Disease in asymptomatic patients with diabetes mellitus.
• To compare these two index tests separately and in combination with a standard reference method - Duplex Ultrasonography of the Lower Limb arteries.

SELECTION OF STUDY SUBJECTS:

Simple randomization

SAMPLE SIZE: assuming a sensitivity of 90%, relative precision of 20%, alpha of 5% and beta of 20%, we have calculated that, 11 patients of PVD are required.

Prevalence of PVD among diabetic patients is considered to be about 10%, so the number of diabetic patients needed will be 110. Applying a non-response rate of 10% , the final number of diabetic patients required for the study is calculated as 122.

 n = 4x [sensitivity ×(1-sensitivity)] / precision²    Minimum number of N=122 cases Sample collected [N]= 150

INCLUSION CRITERIA:

Adults diagnosed with Diabetes as per American Diabetes Association criteria, irrespective of duration, type of diabetes, glycemic control or presence of complications.

EXCLUSION CRTITERIA:

• Symptomatic Diabetic Peripheral Vascular Disease (PVD).
• Patients previously diagnosed with PVD or with symptoms of PVD such as claudication pain, swelling, ulcers, gangrene or previous history of amputations.
• Any significant prior medical history of hyper-coagulable states, congestive heart failure, suspected arteritis or collagen vascular diseases and other PVD.
• Patients who are unable to lie supine during the period of testing.
• Patients who are extremely sick requiring care in intensive care units

DATA COLLECTION

Study Design and Setting:

We conducted a cross-sectional observational study at the Gulbarga Institute of Medical Sciences (GIMS), Kalaburgi, from August 2022 to July 2024. The study included patients with Diabetes Mellitus who attended the outpatient and inpatient departments.

Participants:

A total of 150 adult patients with Diabetes Mellitus were included in the study, selected based on specific inclusion criteria. The sample size was calculated assuming a sensitivity of 90%, relative precision of 20%, and a non-response rate of 10%. A minimum of 122 patients was required, based on an estimated 10% prevalence of Peripheral Vascular Disease (PVD) in diabetic patients.

Methodology:

Following ethical committee clearance and written informed consent, patients were enrolled in the study. A detailed medical history and clinical examination were conducted. The following assessments were carried out:

Pulse Oximetry:

Readings were recorded from both the right and left middle fingers and great toes in a supine position. The oxygen saturation levels were measured at baseline, and then after elevating each lower limb by 12 inches.

Ankle-Brachial Index (ABI):

ABI was measured using a sphygmomanometer. Blood pressure was recorded first from both arms and then from both legs. The higher ankle pressure (from either the dorsalis pedis or posterior tibial arteries) was compared with the brachial pressure to calculate the ABI for each limb.

Duplex Ultrasonography:

Patients underwent duplex ultrasonography of both lower limb arteries within a week of pulse oximetry and ABI assessments. The radiologist recorded the peak systolic velocities of the arteries to confirm PVD.

This multi-step approach allowed for a comprehensive evaluation of PVD using both non-invasive methods (pulse oximetry and ABI) and the gold-standard diagnostic tool (duplex ultrasonography).

Table 1: GENDER

Table 2: RESIDENCE

Table 3: AGE GROUP

Table 4: DURATION OF DISEASE

Table 5: ALCOHOL IN TAKE

Table 6: SMOKER

Table 7: COMORBIDITIES

Table 8: TREATMENT

Table 9: BODY MASS INDEX (BMI)

Table 10: GLYCEMIC CONTROL

Table 11: VITAL SIGNS

Table 12: ANKLE BRACHIAL INDEX

Table 13: PERIPHERAL VASCULAR DISEASE (PVD) BASED ON ABI

Table 14: PVD BASED ON PULSE OXIMETRY

Table 15: USG DOPPLER FINDINGS

Table 16: COMPARISON OF PVD - ABI WITH USG DOPPLER

Table 17: COMPARISON OF PVD BY PULSE OXIMETRY WITH USG DOPPLER

In this study, the mean age of participants was 58.91 years, with a majority in the 51-60 age group (40.7%). This aligns with previous studies, such as Premalatha G et al., which also identified a higher prevalence of peripheral vascular disease (PVD) in older age groups, especially those over 50. Our findings confirm that age is a significant risk factor for PVD among diabetic patients, with middle-aged and older adults being more affected[23].

Regarding gender, our study showed a predominance of males (62%) over females (38%), similar to other studies by Huysman F et al. (60%) and Premalatha G et al. (65%). This suggests that males are at a higher risk of developing PVD [23,24].

When analyzing residency, our study found an almost equal distribution between rural (52%) and urban (48%) residents. This mirrors findings by Sarangi S et al., who reported a slightly higher prevalence in rural areas. Limited access to healthcare facilities in rural settings could contribute to this higher prevalence[25]

The average duration of diabetes in our study was 9.22 years. Studies by Selvin E et al. and Kumar MS et al. report similar findings, reinforcing the importance of long-term diabetes duration in the development of PVD. The risk of PVD increases significantly after 6-10 years of diabetes[26,27].

Our study also found a mean BMI of 24.38, consistent with findings from Newman AB et al. and Fisher MR et al., which suggest that a higher BMI is a contributing factor to PVD [28,31].

In terms of glycemic control, the mean HbA1c in our study was 8.68%, with fasting and postprandial blood sugar levels of 167.45 mg/dL and 246.43 mg/dL, respectively. These values align with those from studies by Beckman JA et al. and Kumar MS et al., indicating that poor glycemic control is a significant risk factor for PVD in diabetic patients [27,29].

Our study also examined vital signs, revealing an average pulse rate of 89.51 bpm and blood pressure values (systolic: 139.09 mmHg, diastolic: 86.92 mmHg). These results are similar to those reported by Huysman F et al. and Premalatha G et al., suggesting that hypertension and elevated pulse rates are common among PVD patients [23,24].

Regarding lifestyle factors, 39.3% of our participants reported alcohol consumption, while 27.3% were current smokers. Both alcohol and smoking have been linked to an increased risk of PVD, as supported by studies from Sarangi S et al. and Huysman F et al [24,25].

Comorbidities were prevalent in our study, with hypertension (52.7%), diabetic retinopathy (19.3%), and diabetic neuropathy (17.3%) being the most common. These findings are consistent with other studies by Sarangi S et al. and Jude EB et al., reinforcing the high burden of comorbidities among diabetic patients with PVD[25,32].

In terms of treatment, the majority of patients in our study (84.7%) were on oral hypoglycemic agents (OHA), similar to the findings of Kumar MS et al. and Premalatha G et al. A small proportion were on insulin or a combination of insulin and OHA, emphasizing the role of oral medications in managing PVD in diabetic patients[23,27].

Regarding diagnostic methods, the Ankle Brachial Index (ABI) was used to diagnose PVD in 24% of our patients. This is consistent with other studies, such as those by Vowden P et al. and Kumar MS et al., which have shown ABI to be a reliable tool for detecting PVD[27,33].

Pulse oximetry also demonstrated a similar diagnostic prevalence (26%), as seen in studies by Gupta S et al. and Huysman F et al., suggesting its effectiveness in screening for PVD[24,30].

Duplex ultrasonography identified PVD in 41.3% of our patients, which is in line with findings from Sarangi S et al. and Premalatha G et al[23,25]. Moreover, the combination of ABI and duplex ultrasonography demonstrated high concordance, with 83.3% of ABI-positive cases confirmed by Doppler. This supports the utility of combining these tools for accurate PVD diagnosis.

Finally, the sensitivity and specificity of pulse oximetry and ABI in our study were consistent with those in the literature, with pulse oximetry showing higher sensitivity but lower specificity compared to ABI. The combined use of both tools, along with duplex ultrasonography, enhances the early detection of PVD, underscoring the importance of a multi-modal approach for accurate diagnosis in diabetic patients.

Limitations

Our study has several limitations. The sample size of 150 patients, while adequate for identifying trends, may not fully represent the broader diabetic population with PVD. Additionally, being conducted at a single center, the findings may not be universally applicable to other healthcare settings. The reliance on self-reported data for variables such as alcohol consumption and smoking status may introduce reporting bias. Finally, while pulse oximetry and ABI were compared to duplex ultrasonography, other diagnostic methods were not considered, which could provide additional insights.

Recommendations

Future research should include larger, multicenter studies to enhance the generalizability of the findings. Longitudinal studies would also be valuable in assessing the progression of PVD in diabetic patients and the long-term efficacy of early detection techniques. Incorporating additional diagnostic tools and biomarkers may offer a more comprehensive understanding of PVD. Moreover, evaluating the cost-effectiveness of pulse oximetry and ABI in routine screening, especially in resource-limited areas, would be beneficial

This study highlights the effectiveness of pulse oximetry and the Ankle Brachial Index (ABI) in detecting Peripheral Vascular Disease (PVD) in asymptomatic diabetic patients. Pulse oximetry demonstrated high sensitivity, making it useful for initial screening, while ABI offered better specificity for accurate diagnosis. When used together and confirmed by duplex ultrasonography, these methods significantly improved PVD detection. These findings emphasize the value of incorporating non-invasive screening tools into routine care for diabetic patients to facilitate early detection and reduce the risk of complications. Additionally, targeted screening of high-risk groups, such as older adults and those with long-standing diabetes, could further improve patient outcomes. The high prevalence of comorbidities like hypertension and diabetic neuropathy underscores the need for a comprehensive approach to diabetes management.

Ethical Clearance:

Approved  by  the  Institute  Ethical  Committee.

Consent:

Informed and written consent from all patients

Funding

None

Authors contribution

Dr. Naveen S Hiremath:  study concept, principle investigator, writing the paper

Dr. Venkatesh Desai: study concept, writing the paper and correction of paper.

Dr. Dayanand Reddi: co-investigator and correction of paper.

Dr. Praveen Kumar: co-investigator and correction of paper.

Conflict of interest

The authors declare having no conflicts of interest for this article

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