Influence of Age, BMI, and Renal Function on Anti-Diabetic Drug Choice: Real-World Data from Eastern India

INTRODUCTION

The management of Type 2 Diabetes Mellitus (T2DM) has shifted from a uniform glucose-centric approach to a personalized, patient-centered model that tailors therapy according to individual characteristics such as age, comorbidities, renal status, and obesity. Contemporary guidelines emphasize optimizing both glycemic control and cardiorenal protection while minimizing treatment-related risks, particularly in elderly patients and those with chronic kidney disease (CKD) or obesity [1–3].

Among clinical parameters, age, body mass index (BMI), and renal function are pivotal determinants of anti-diabetic drug selection. Aging alters drug metabolism and increases susceptibility to hypoglycemia, necessitating cautious use of insulin and sulfonylureas [4]. BMI not only reflects disease phenotype but also influences drug response — overweight or obese patients benefit from weight-reducing agents such as sodium–glucose co-transporter-2 (SGLT-2) inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1 RAs), which also confer cardiovascular and renal protection [5]. Conversely, underweight individuals or those with advanced disease often require insulin therapy [6].

Renal function, typically assessed through estimated glomerular filtration rate (eGFR), critically impacts both drug choice and dosing. While metformin remains the first-line agent, its use is restricted in moderate-to-severe renal impairment. SGLT-2 inhibitors and certain DPP-4 inhibitors are now recognized for their nephroprotective benefits, yet require careful use at lower eGFR thresholds [7–9].

Despite robust international and national guidelines, including the National Programme for Prevention and Control of Cancer, Diabetes, Cardiovascular Diseases and Stroke (NPCDCS) in India [10], real-world prescribing often diverges from evidence-based recommendations. Factors such as drug cost, limited availability, and inadequate awareness contribute to underuse of newer agents in low- and middle-income settings.

The present study was conducted in a tertiary care hospital in Eastern India to examine how age, BMI, and renal function influence anti-diabetic drug prescribing in real-world practice. It also aimed to identify deviations from guideline-recommended personalized diabetes management, providing insights relevant to both clinicians and policymakers.

METHOD

A cross-sectional, observational study was conducted over a six-month period (January–June 2023) in the General Medicine Outpatient Department in collaboration with the Department of Pharmacology at Calcutta National Medical College, Kolkata, Eastern India. The study was approved by the Institutional Ethics Committee, and all participants provided written informed consent prior to enrolment.

A total of 150 adult patients (≥18 years) with a confirmed diagnosis of Type 2 Diabetes Mellitus (T2DM) and receiving at least one anti-diabetic medication were included using convenience sampling. The sample size was chosen based on feasibility and comparability with similar hospital-based observational studies on prescribing patterns.

Exclusion criteria included pregnant or lactating women and patients who were acutely ill or unwilling to participate.

Data were collected using a structured Case Record Form (CRF), which combined information from outpatient prescriptions, hospital records, and direct patient interviews. Collected parameters included:

• Demographic data: age, sex, height, weight

• Clinical data: duration of diabetes, comorbidities, and renal profile

The Body Mass Index (BMI) was calculated as:

and categorized according to WHO criteria:

• Underweight: <18.5 kg/m²

• Normal: 18.5–24.9 kg/m²

• Overweight: 25.0–29.9 kg/m²

• Obese: ≥30.0 kg/m²

Renal function was assessed by estimated Glomerular Filtration Rate (eGFR), calculated using the CKD-EPI equation based on serum creatinine values. Patients were classified as:

• Normal renal function: eGFR >90 mL/min/1.73 m²

• Mild impairment: eGFR 60–90 mL/min/1.73 m²

• Moderate impairment: eGFR 30–60 mL/min/1.73 m²

Serum urea was recorded for completeness but excluded from statistical analysis due to limited specificity in renal staging.

Prescribed medications were grouped into major anti-diabetic drug classes following the American Diabetes Association (ADA) 2022 and ESC/EASD 2019 guidelines:

• Biguanides (Metformin)

• Sulfonylureas

• DPP-4 inhibitors

• SGLT-2 inhibitors

• GLP-1 receptor agonists

• Insulin preparations

The proportion of patients receiving each class was analyzed across subgroups defined by age, gender, BMI, and renal function.

All data were double-entered and cross-verified by two independent researchers to minimize transcription errors. Incomplete or inconsistent records were excluded before analysis.

Data were entered into IBM SPSS Statistics (Version 28.0.1.1) for analysis. Descriptive statistics were applied:

• Continuous variables were summarized as mean ± standard deviation (SD).

• Categorical variables were presented as frequencies and percentages. The study was designed as descriptive, and no inferential statistical tests (e.g., p-values) were performed.

Ethical approval was obtained prior to data collection. Participant confidentiality was maintained throughout the study, and all procedures adhered to the principles of the Declaration of Helsinki (2013 revision).

RESULT

A total of 150 patients with Type 2 Diabetes Mellitus (T2DM) were included in the analysis. The mean age of the participants was 56.3 ± 10.4 years, mean BMI 27.1 ± 4.6 kg/m², and mean estimated glomerular filtration rate (eGFR) 78.2 ± 18.9 mL/min/1.73 m². Among them, 69 (46.0%) were males and 81 (54.0%) were females.

Age-wise Distribution (Table 1)

Table 1. Age-wise Distribution of Anti-Diabetic Drug Prescriptions (n = 150)
Age Group (years)	n (%)	Metformin	DPP-4 Inhibitors	Sulfonylureas	SGLT-2 Inhibitors	Insulin
20–40	18 (12.0)	83.3 %	50.0 %	38.9 %	5.6 %	0.0 %
41–60	96 (64.0)	85.4 %	64.6 %	52.1 %	5.2 %	6.3 %
61–80	36 (24.0)	88.9 %	72.2 %	55.6 %	5.6 %	11.1 %

Metformin was the most frequently prescribed anti-diabetic agent across all age groups, with slightly higher use among older adults (83.3% in 20–40 years vs. 88.9% in 61–80 years). The prescription of DPP-4 inhibitors also increased with advancing age, from 50.0% in younger adults to 72.2% among the elderly. In contrast, insulin therapy appeared predominantly in the older population (11.1% in 61–80 years), reflecting disease progression and declining β-cell function. The use of SGLT-2 inhibitors remained consistently low (≈5%) across all age categories.

Gender-wise Distribution (Table 2)

Table 2. Gender-wise Distribution of Anti-Diabetic Drug Prescriptions (n = 150)
Gender	n (%)	Metformin	DPP-4 Inhibitors	Sulfonylureas	SGLT-2 Inhibitors	Insulin
Male	69 (46.0)	87.0 %	65.2 %	55.1 %	5.8 %	7.2 %
Female	81 (54.0)	84.0 %	61.7 %	48.1 %	4.9 %	6.2 %

Minor variations were noted between genders. Males received marginally more DPP-4 inhibitors (65.2% vs. 61.7%) and sulfonylureas (55.1% vs. 48.1%) compared to females. Metformin use was nearly universal in both groups (87.0% in males and 84.0% in females). Differences between genders were small and not subjected to inferential analysis due to the descriptive design.

BMI-wise Distribution (Table 3)

Table 3. BMI-wise Distribution of Anti-Diabetic Drug Prescriptions (n = 150)
BMI Category (kg/m²)	n (%)	Metformin	DPP-4 Inhibitors	Sulfonylureas	SGLT-2 Inhibitors	Insulin
< 18.5 (Underweight)	6 (4.0)	66.7 %	50.0 %	33.3 %	0.0 %	16.7 %
18.5–24.9 (Normal)	40 (26.7)	82.5 %	60.0 %	45.0 %	4.0 %	4.0 %
25.0–29.9 (Overweight)	59 (39.3)	87.8 %	67.3 %	55.1 %	5.1 %	6.1 %
≥ 30.0 (Obese)	45 (30.0)	92.3 %	73.1 %	57.7 %	7.7 %	11.5 %

A majority of the study population was either overweight (39.3%) or obese (30.0%). Metformin use showed a positive association with BMI, ranging from 66.7% in underweight to 92.3% in obese patients. A similar trend was observed for DPP-4 inhibitors (50.0% in underweight vs. 73.1% in obese). Insulin therapy was most frequent among underweight individuals (16.7%), likely indicating advanced disease or poor glycemic control. Despite strong evidence supporting their use in overweight and obese patients, SGLT-2 inhibitors were prescribed in fewer than 8% of these groups.

Renal Function-based Distribution (Table 4)

Table 4. Distribution of Anti-Diabetic Drug Prescriptions by Renal Function (n = 150)
eGFR Category (mL/min/1.73 m²)	n (%)	Metformin	DPP-4 Inhibitors	Sulfonylureas	SGLT-2 Inhibitors	Insulin
> 90 (Normal)	74 (49.3)	90.5 %	67.6 %	51.4 %	6.8 %	5.4 %
60–90 (Mild impairment)	63 (42.0)	80.9 %	63.5 %	50.8 %	3.2 %	7.9 %
30–60 (Moderate impairment)	13 (8.7)	69.2 %	53.8 %	46.2 %	0.0 %	30.8 %

Renal function exerted a clear influence on drug selection. Among patients with normal eGFR (>90 mL/min/1.73 m²), metformin use was highest (90.5%), while its use declined progressively in mild (80.9%) and moderate (69.2%) renal impairment. Conversely, insulin prescribing increased sharply with worsening renal function, reaching 30.8% in patients with moderate impairment (eGFR 30–60 mL/min/1.73 m²). The use of SGLT-2 inhibitors was notably absent in this subgroup, despite current evidence supporting their safety and efficacy in patients with mild-to-moderate chronic kidney disease.

Overall Prescription Trends

Across the study population, metformin remained the cornerstone therapy (86.7%), followed by DPP-4 inhibitors (64%) and sulfonylureas (52%). SGLT-2 inhibitors were underutilized across all demographic and clinical groups, while insulin use was more common among elderly, underweight, and renally impaired patients. These patterns reflect partial adherence to individualized therapy but highlight a persistent gap between guideline recommendations and real-world prescribing behavior.

Metformin was the most prescribed agent across all age groups, with increasing insulin use in older patients.

Gender-based variations were minor and not statistically analyzed.

Use of SGLT-2 inhibitors increased modestly with BMI but remained below 8 % even in obese patients.

Insulin use increased markedly with worsening renal function, whereas no SGLT-2 inhibitor was prescribed below eGFR 60.

DISCUSSION

This study evaluated how age, body mass index (BMI), and renal function influence anti-diabetic drug prescribing patterns in a tertiary care hospital in Eastern India. The findings demonstrate that while prescribing trends generally reflect individualized therapeutic approaches, notable gaps persist between real-world practice and evidence-based recommendations—particularly concerning the underuse of SGLT-2 inhibitors and GLP-1 receptor agonists.

Major Findings

Metformin remained the cornerstone of therapy across all patient subgroups, reaffirming its role as the first-line agent in Type 2 Diabetes Mellitus (T2DM). DPP-4 inhibitors were frequently co-prescribed, especially among elderly and obese patients, whereas sulfonylureas and insulin were more commonly used in older or underweight individuals. Declining renal function was associated with reduced metformin use and increased insulin prescribing. However, the absence of SGLT-2 inhibitor prescriptions among patients with impaired renal function and the complete lack of GLP-1 receptor agonist use highlight a significant evidence–practice gap in this region.

Age-related Trends

Advancing age was associated with greater use of DPP-4 inhibitors and insulin, reflecting clinicians’ awareness of hypoglycemia risk and β-cell exhaustion in older adults. These findings align with prior Indian and global studies reporting similar trends [11,12]. The relatively high prevalence of sulfonylurea use in elderly patients, however, remains concerning given their association with severe hypoglycemia and cardiovascular events [13]. Greater adoption of low-risk agents such as DPP-4 inhibitors or fixed-dose combinations could improve safety in this vulnerable group.

BMI and Drug Selection

BMI had a clear influence on therapeutic choice, with obese and overweight patients more likely to receive metformin and DPP-4 inhibitors. Yet, despite their strong weight-lowering and cardio-renal benefits, SGLT-2 inhibitors and GLP-1 receptor agonists were rarely prescribed—consistent with national data showing cost and accessibility barriers in India [14]. Underweight individuals were more often prescribed insulin, likely due to long-standing disease or poor β-cell reserve. These findings reinforce the need for enhanced physician awareness and patient education regarding the dual metabolic and cardiovascular advantages of newer drug classes.

Renal Function and Prescribing Behavior

Renal function emerged as a decisive factor influencing therapeutic choice. Metformin use appropriately declined with worsening renal function, while insulin prescribing increased among those with moderate impairment—findings consistent with safety recommendations [7]. However, none of the patients with eGFR < 60 mL/min/1.73 m² received SGLT-2 inhibitors, despite robust evidence from large clinical trials such as CREDENCE and DAPA-CKD supporting their renoprotective efficacy even in moderate CKD [8,9]. This underuse likely stems from limited availability, higher cost, and lingering safety misconceptions at the point of care.

Gender and Prescribing Variation

Gender differences were minimal and not statistically explored in this descriptive analysis. Nonetheless, previous research has shown that physician perceptions of cardiovascular risk may differ between men and women, potentially influencing therapeutic decisions [15]. Larger, analytic studies are warranted to explore such nuances in the Indian context.

PRACTICE AND POLICY IMPLICATIONS

The observed prescribing trends suggest partial movement toward patient-centered diabetes management but underscore persistent barriers to the rational use of guideline-endorsed therapies. Aligning real-world practice with recommendations from the National Programme for Prevention and Control of Cancer, Diabetes, Cardiovascular Diseases and Stroke (NPCDCS) and international bodies such as the ADA and ESC/EASD is essential for improving outcomes in Indian settings [10]. Regular prescription audits, inclusion of SGLT-2 inhibitors and GLP-1 RAs in essential drug lists, and continuing medical education could enhance adherence to evidence-based practices. Policy-level initiatives to reduce drug costs and improve public-sector availability would further support equitable access to modern diabetes care.

STRENGTHS AND LIMITATIONS

This study provides real-world insights into prescribing behavior in a tertiary hospital setting, integrating demographic and clinical variables often underreported in Indian data. However, the cross-sectional design and convenience sampling limit causal inference and generalizability. The absence of inferential statistics, small subgroup sizes, and lack of data on prescriber rationale or socioeconomic influences are additional constraints. Nevertheless, these findings serve as a valuable foundation for future multicentric and longitudinal research on personalized diabetes therapy in resource-limited settings.

CONCLUSION

This study confirms that demographic and clinical characteristics—age, BMI, and renal function—significantly influence the selection of anti-diabetic drugs in patients with Type 2 Diabetes Mellitus. The results reflect an emerging trend toward personalized prescribing; however, inconsistencies with guideline-recommended practices persist, particularly regarding the use of SGLT-2 inhibitors in high-risk populations.

The findings call for a dual approach: reinforcing clinician awareness and patient-centered prescribing, while also addressing systemic limitations such as drug availability and cost. Future research should adopt multicenter, longitudinal designs to evaluate therapeutic outcomes and guide interventions that promote rational, equitable, and personalized diabetes care in diverse populations.

Conflict of interest – None

Funding – Self

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