European Journal of Cardiovascular Medicine

Type 2 Diabetes Mellitus (T2DM) is a chronic, progressive metabolic disorder marked by insulin resistance and β-cell dysfunction, resulting in persistent hyperglycemia. Globally, diabetes poses a substantial public health burden, with the International Diabetes Federation reporting over 537 million adults affected as of 2021—a number expected to escalate in the coming decades. In India alone, more than 77 million individuals live with diabetes, necessitating urgent and effective management strategies to address this rising epidemic.

Oral hypoglycemic agents (OHAs) continue to be the foundation of pharmacological treatment for T2DM, particularly during the early and moderate stages of disease progression. Drugs such as metformin, sulfonylureas, and DPP-4 inhibitors are widely favored for their proven efficacy, affordability, and favorable safety profiles. Nevertheless, clinical success in diabetes management is not solely determined by the pharmacological properties of these agents; patient adherence to prescribed regimens plays an equally pivotal role in achieving glycemic targets [1,2].

Medication adherence—defined as the extent to which patients follow prescribed drug regimens in terms of dose, timing, and frequency—is frequently suboptimal in T2DM populations. Studies have consistently shown that poor adherence significantly undermines glycemic control, contributes to disease-related complications, and escalates healthcare costs [3,4]. Key factors influencing non-adherence include forgetfulness, medication side effects, financial constraints, and inadequate disease awareness [1,2,5].

Evidence indicates that even modest improvements in adherence can yield substantial reductions in HbA1c levels and mitigate long-term complications [5,6]. Therefore, evaluating real-world adherence patterns and identifying modifiable barriers is crucial for designing targeted interventions that enhance treatment outcomes and reduce the clinical burden of T2DM.

In this context, understanding real-world patterns of medication adherence and their impact on glycemic control among T2DM patients using OHAs is essential for tailoring individualized care strategies. The present study aimed to evaluate medication adherence using the validated 8-item Morisky Medication Adherence Scale (MMAS-8), assess treatment regimens and side effects, and explore the association between adherence and glycemic outcomes as measured by HbA1c levels. The findings are expected to inform interventions that improve adherence and optimize diabetes management in routine clinical practice.

Study Design and Setting

This was a hospital-based, cross-sectional observational study conducted at Mamata Medical College and Hospital, located in Khammam, Telangana, India. The study was carried out over a six-month period from June 2024 to November 2024.

Study Population

The study included adult patients (aged ≥18 years) diagnosed with Type 2 Diabetes Mellitus (T2DM) who had been on oral hypoglycemic agents (OHAs) for at least six months prior to enrollment. Patients were recruited from the outpatient and inpatient departments of General Medicine and Endocrinology.

Inclusion Criteria

Diagnosed cases of T2DM (based on ADA criteria)

Age 18 years or older

On a stable regimen of oral hypoglycemic agents for ≥6 months

Willing to participate and provide informed consent

Exclusion Criteria

Patients on insulin therapy or newly diagnosed with T2DM (<6 months)

Pregnant or lactating women

Individuals with cognitive impairment or psychiatric illness affecting the ability to respond accurately

Patients with severe complications (e.g., end-stage renal disease, hepatic failure)

Sample Size and Sampling Method

A total of 100 patients were included using a convenient sampling technique. All eligible and consenting patients visiting the hospital during the study period were approached until the sample size was met.

Data Collection Tools and Procedure

Data were collected using a structured proforma, which included three components:

Demographic and clinical details: age, sex, duration of diabetes, comorbidities, current medication regimen.

Medication adherence assessment: measured using the 8-item Morisky Medication Adherence Scale (MMAS-8). Scores were categorized as:

High adherence: score = 8

Medium adherence: score 6–7

Low adherence: score <6

Glycemic control: evaluated using the most recent HbA1c level(within 1 month of the interview), extracted from laboratory records.

Patients were interviewed face-to-face by trained researchers after obtaining written informed consent. Additional information on treatment regimens, side effects, and lifestyle practices (exercise, diet adherence) was gathered.

Ethical Considerations

The study was approved by the Institutional Ethics Committee (IEC) of Mamata Medical College(MMC/IEC/2022/2945/10/2025), Khammam. Written informed consent was obtained from all participants. Confidentiality of patient data was strictly maintained.

Statistical Analysis

Data were entered into Microsoft Excel and analyzed using SPSS version 25.0. Descriptive statistics were used to summarize patient characteristics, adherence levels, and glycemic outcomes. The Chi-square test was used to evaluate the association between medication adherence and glycemic control. A p-value < 0.05 was considered statistically significant.

A total of 100 patients with Type 2 Diabetes Mellitus (T2DM), all of whom had been on oral hypoglycemic agents (OHAs) for at least six months, were enrolled in the study. The mean age of participants was 56.4 ± 9.2 years, and the majority were male (60%) (Table 1).

Table 1: Demographic Characteristics of Study Participants (N = 100)

Medication Adherence

Medication adherence, assessed using the 8-item Morisky Medication Adherence Scale (MMAS-8), revealed that 28% of patients demonstrated high adherence (score = 8), 46% had medium adherence (score 6–7), and 26% had low adherence (score <6) (Table 2).

Table 2: Medication Adherence Level (MMAS-8 Score)

Figure 1.Medication Adherence Level (MMAS-8 Score)

Among the 72 patients with medium or low adherence, forgetfulness was the most frequently reported barrier (54%), followed by medication cost (18%), lack of awareness (14%), and other reasons such as complexity of regimen or perceived side effects (14%) (Table 3).

Table 3: Reasons for Low or Medium Medication Adherence

Figure 2. Reasons for Low or Medium Medication Adherence

Glycemic Control

Glycemic control was evaluated using the most recent HbA1c levels. Good control (HbA1c <7%) was observed in 32% of patients, moderate control (HbA1c 7–8%) in 40%, and poor control (HbA1c >8%) in 28% of the cohort (Table 4).

Table 4: Glycemic Control Based on HbA1c Levels

Figure 3.Glycemic Control Based on HbA1c Levels

A statistically significant association was found between medication adherence and glycemic outcomes (p < 0.01), with 64% of patients in the high adherence group achieving good glycemic control compared to only 8% in the low adherence group (Table 5).

Table 5: Association Between Medication Adherence and Glycemic Control

Figure 4.Association Between Medication Adherence and Glycemic Control

Treatment Regimens

The most commonly prescribed regimen was metformin monotherapy, accounting for 38% of the participants. This was followed by combination therapies: sulfonylurea plus metformin (34%), DPP-4 inhibitor plus metformin (18%), and triple therapy (metformin, sulfonylurea, and DPP-4 inhibitor) in 10% of patients (Table 6).

Table 6: Distribution of Treatment Regimens

Figure 5.Distribution of Treatment Regimens

While combination therapy groups showed slightly better HbA1c levels, they also tended to have lower adherence, particularly in the triple therapy group.

Adverse Effects

A total of 15 patients (15%) reported experiencing adverse effects, with gastrointestinal symptoms linked to metformin being the most common (9%). Hypoglycemic episodes associated with sulfonylureas were reported by 4% of participants, and other side effects such as headache or fatigue were observed in 2% (Table 7).

Table 7: Reported Adverse Effects

Figure 6.Reported Adverse Effects of Oral Hypoglycemic Agents

Lifestyle Factors

Among the participants, 45% reported engaging in regular physical activity (defined as >150 minutes/week), and 52% adhered to dietary recommendations as verified by a dietitian. Patients who followed both physical activity and dietary guidelines generally demonstrated better glycemic profiles; however, these associations were not independently significant in multivariate analysis (Table 8).

Table 8: Lifestyle Factors Among T2DM Patients

Figure 7.Lifestyle Factors Among T2DM Patients

This study presents a real-world evaluation of medication adherence and its impact on glycemic outcomes in patients with Type 2 Diabetes Mellitus (T2DM) using oral hypoglycemic agents (OHAs). The findings reaffirm the strong link between adherence levels and glycemic control, emphasizing the essential role of consistent medication-taking behavior in diabetes management.

Only 28% of participants in this study demonstrated high adherence according to the MMAS-8, a finding consistent with earlier investigations reporting suboptimal adherence in 30%–60% of T2DM patients across diverse settings [7,8]. The most common reason for non-adherence was forgetfulness, followed by high medication costs and lack of awareness, reflecting the multifactorial nature of adherence challenges as previously reported in similar contexts [9,10]. These findings underline the persistent global and regional barriers to optimal medication use, even when effective therapies are available.

Glycemic control, as assessed by HbA1c, was optimal in only one-third of participants. Notably, 64% of patients with high adherence achieved target glycemic levels (<7%), compared to just 8% in the low-adherence group. This gradient highlights the clinical importance of adherence and corroborates findings from prior reviews and meta-analyses that associate good adherence with significantly improved glycemic indices and reduced complication risks [11,12].

The influence of treatment regimen complexity was also evident. Metformin monotherapy was the most common regimen (38%), with adherence declining as the number of medications increased. This inverse association between polypharmacy and adherence aligns with existing literature, which identifies regimen complexity as a key predictor of non-adherence [13]. Addressing this through regimen simplification and patient-centric prescribing may enhance compliance without compromising therapeutic efficacy.

Adverse effects were reported by 15% of patients, with gastrointestinal symptoms from metformin and hypoglycemia from sulfonylureas being predominant. Similar tolerability concerns have been documented in prior studies and are known to negatively impact persistence and adherence [14]. Timely management of side effects, patient counseling, and consideration of better-tolerated alternatives may therefore help retain patients in long-term therapy.

While lifestyle factors like regular physical activity and diet adherence were associated with better glycemic profiles in univariate analysis, they did not independently predict glycemic outcomes. Nonetheless, lifestyle modification remains a cornerstone of T2DM management and should be promoted alongside pharmacological adherence in patient education programs.

This study is strengthened by the use of a validated adherence tool (MMAS-8), detailed treatment profiling, and assessment of both behavioral and pharmacologic factors. However, limitations include the cross-sectional design, recall bias inherent to self-reported data, and the single-center setting, which may limit generalizability.

This study highlights the significant impact of medication adherence on glycemic control among patients with Type 2 Diabetes Mellitus using oral hypoglycemic agents. High adherence was strongly associated with better HbA1c outcomes, while forgetfulness, medication cost, and lack of awareness were key barriers to compliance. Metformin-based regimens were common, though adherence declined with increasing regimen complexity. Although lifestyle modifications supported glycemic control, medication adherence remained the strongest predictor. These findings emphasize the urgent need for targeted interventions—such as patient education, simplified regimens, and regular follow-up—to improve adherence and overall treatment outcomes. Strengthening adherence strategies is essential for effective and sustainable diabetes management in real-world clinical practice.

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