Real-world evaluation of dosing and haemoglobin A1c (HbA1c) in patients converted from insulin glargine (Lantus®) to insulin glargine (Basaglar®) in Saudi Arabia
Published on 23 March 2026
Generics and Biosimilars Initiative Journal (GaBI Journal). 2026;15(1).
Introduction/Study objective: About 28% of Saudi Arabia population above 15 years old are diagnosed with diabetes. Basal insulin glargine Lantus and its’ biosimilar Basaglar, are long-acting insulin that regulate blood glucose levels over 24 hours. Patients switch between basal insulins for various reasons including adverse events, availability and cost. Switching should be done with careful dosing titration to avoid complications and achieve successful therapy continuation. We aim to describe dosing characteristics and haemoglobin A1C (HbA1c) levels in patients switching medications from Lantus to Basaglar in Saudi Arabia. |
Introduction
Recent estimation of diabetes prevalence worldwide reaches up to 10.5% among adults above 20 years of age [1]. In Saudi Arabia, it is estimated that 28% of the population aged ≥15 years are diagnosed with diabetes [2]. In type 1 diabetes mellitus (T1DM), the pancreas does not produce insulin as in healthy individuals. In type 2 diabetes mellitus, insulin is produced by the pancreas, but the body cells resist it [3]. Both types of diabetes cause elevated blood glucose levels since glucose is not utilized by the body cells. Therefore, affected individuals often require insulin injections to manage blood glucose levels and prevent complications [3].
According to the American Diabetes Association (ADA), Saudi Diabetes Society, and Saudi Diabetes Practice Guidelines, T2DM patients should initially be managed with oral glucose-lowering medications for blood glucose regulation, alongside diet and lifestyle modification [4]. All T1DM patients and T2DM Patients whose condition requires intensified treatment are prescribed basal insulin therapy [4, 5]. Basal insulin is a synthetic injectable that mimics endogenous insulin in achieving target basal levels of insulin in the body without causing hypoglycaemia [6]. Different types of insulin (short-acting, intermediate-acting, and long-acting) are based on the glucose-lowering effect’s beginning, peak, and lasting duration. Long-acting insulin reaches the blood circulation several hours after injection and keeps blood glucose levels regulated over a 24-hour duration. Types of long-acting insulin include degludec (Tresiba®), detemir (Levemir®), and glargine (Basaglar®, Lantus®) [3].
Over the past two decades, administering basal insulin injections once daily was facilitated as long-acting basal insulin analogs glargine and detemir were introduced in the market [7]. Basal insulin glargine of first-generation (glargine 100 units) and second-generation (glargine 300 units/mL) allow longer durations of regulated blood glucose levels and less risk of hypoglycaemia in comparison with intermediate-acting insulin, as demonstrated in clinical studies [8, 9]. Among basal insulins, the largest market share is insulin glargine [10–13].
Insulin glargine Basaglar® (by Eli Lilly and Company) was introduced as the first insulin biosimilar to its originator reference product, insulin glargine Lantus® (by Sanofi Aventis) [14, 15]. Basaglar® is similar to Lantus® in its amino acid sequence, pharmacokinetics, and pharmacodynamics [16–19]. In 2014, Basaglar® received marketing approval in the United States and the European Union [14, 15]. Afterwards, in 2015, Basaglar® received marketing approval in Saudi Arabia [20]. According to Saudi Food and Drug Authority (SFDA) reports, insulin glargine Basaglar® use has increased since its registration in 2019 [20].
The motivation for switching to biosimilars is primarily driven by the need to reduce healthcare costs and improve patient access to biological therapies [21]. Biosimilars offer a lower-cost alternative to expensive biological drugs, leading to significant savings for healthcare systems, insurance providers, and patients [21]. This increased affordability enhances access to life-saving treatments for a broader patient population, particularly in low- and middle-income regions [22]. Additionally, introducing biosimilars fosters market competition, driving down prices of reference biologicals and encouraging further innovation [23]. With proven efficacy and safety profiles comparable to their reference products, biosimilars present a sustainable solution for managing healthcare expenditures while maintaining high standards of patient care [24, 25]. Patients switch between basal insulins for various reasons, including adverse events, product availability, and cost [24]. A recent study conducted in Saudi Arabia described the significant cost-effectiveness of switching from Lantus® to Basaglar® without compromising the quality of care [25]. On the other hand, switching between insulin biosimilars should be done with careful dosing transition to minimize the risk of hyperglycaemia/hypoglycaemia and other possible adverse effects [4, 26]. Successful medication switch involves frequent monitoring of blood glucose levels and careful insulin titration in the first weeks following treatment conversion [4, 26]. According to the literature and a medication switch guidance recently published in 2021, there should be no change between the doses if the medication switch is between different insulin glargine 100 units/mL products such as Lantus® and Basaglar® [5, 27, 28].
Since the approval of insulin biosimilar Basaglar®, numerous post-marketing efficacy and safety studies have been comparing the two products in different countries [29]. In Saudi Arabia, a recently published research describing differences between Lantus® and Basaglar® from a financial standpoint showed significant cost-effectiveness for patients who switch treatment to Basaglar® [25], which is reported as one of the main reasons patients switch medications globally [30]. However, it appears that the literature still lacks real-world practice characteristics regarding biosimilar dosing and health outcomes. Two recent real-world studies using health records described conversion treatment dosing and health outcomes [31, 32]. One study showed no significant change compared to baseline values [31], while the other study recorded significant differences in pre-and post-conversion doses [32].
Study objective
To assess dosing practices during conversion from insulin glargine Lantus® to biosimilar Basaglar® and to evaluate changes in HbA1c levels following the medication switch in routine clinical practice in Saudi Arabia.
Methods
Study design
Non-interventional, retrospective secondary data analysis study using data from electronic medical records of patients who switched from Lantus® to Basaglar®.
Data collection/source
Data from electronic medical records of patients who switched from Lantus® to Basaglar® from 1 January 2020 to 31 December 2022 was extracted using the SFDA Real-world Evidence Research Network [13]. This database is derived from multi-region healthcare centres in Saudi Arabia. Data was received after acquiring the Institutional Review Boards’ approval (IRB# 2023_15).
Study sample
Inclusion criteria
The study included patients at least 18 years old with an ICD-10 diagnosis code for T1DM or T2DM. Participants had undergone a treatment conversion from insulin glargine Lantus® (LGlar) to biosimilar insulin glargine Basaglar® (BGlar) as part of usual practice within the study period, from the beginning of 2020 to the end of 2022. To qualify, patients must have been using LGlar for at least six months with recorded HbA1c levels within the six months preceding the switch (pre-switch period) and must have had follow-up visits within the six months following the switch to BGlar (post-switch period).
Exclusion criteria
Patients who did not meet the inclusion for the study outcomes within the described study timeline were excluded.
Variables
The variables in the study included demographic information such as age, gender (male or female), and region. The medical condition history of participants was recorded, including the date of diagnosis for type 1 diabetes mellitus (ICD10 code E10.9) and type 2 diabetes mellitus (ICD10 code E11.9). Medication history included the start date and dose (units/mL) of Lantus® prescriptions, as well as the start date (index date) and dose (units/mL) of Basaglar® prescriptions. Health parameters included HbA1c levels measured approximately six months before and six months after the index date (the start date of Basaglar®).
Outcomes
a) Describing dosing practices at the time of switching from Lantus® to Basaglar®, specifically whether dose concentration (100 units/mL) was maintained according to switching recommendations.
b) Assessment of HbA1c levels between the 6-month pre-switch and 6-month post-switch periods.
Statistical analysis
Data were analysed using descriptive statistics. Continuous variables were presented as means with standard deviations (SD) for the full sample. Categorical or binary variables were presented as frequency and incidence rates. Reported values include median with interquartile range, mean with standard deviation, frequency, and test of variance from baseline calculated with a 95% CI. For comparisons made between baseline and post-baseline within each group, a paired t-test was conducted using a <0.05 significance level where applicable for reference purposes. Statistical analysis was conducted using Statistical Package for Social Sciences (SPSS) version 26.0.
Results
Data from a total of 879 patients has been included in this study. Two groups of patients were identified in this study based on their insulin treatment conversion. The first group (Group 1) consists of patients who switched from Insulin glargine Lantus® to insulin biosimilar Basaglar® (n = 579). The second group of patients (Group 2) consists of patients who switched from Lantus® to an alternating treatment between Lantus® and Basaglar®, see Figure 1.
The median age of the study population is 57 (±21) for the first group and 58 (±22) for the second group. This study shows almost equal representation of genders in both groups, with female gender constituting [324 (56%)] of the first group and [175 (58%)] of the second group. Region distribution of patients was mainly in the Central region [382 (66%)] and Western region [123 (42%)] for the first and second groups, respectively, as shown in Tables 1 and 2 for demographics.
Concerning treatment conversion dosage, we have found that all the enrolled patients in this study (N = 879) were switched to Basaglar® with an initiation dose of 100 units/mL within the 6 months following the medication switch.
Patients who switched completely from Lantus® to Basaglar® (n = 579) had a mean HbA1c of 9.2 (±2) in the 6 months prior to switching and 8.8 (±1.9) in the 6 months after switching (p < 0.001; 95% CI: 0.29–0.55), see Table 1. Similarly, patients alternating between Lantus® and Basaglar® (n = 300) had a mean HbA1c of 9.4 (±2.2) before switching and 8.8 (±1.9) afterward (p < 0.001; 95% CI: 0.42–0.85), see Table 2.
In both groups, HbA1c levels remained above recommended glycaemic targets before and after switching, indicating overall suboptimal diabetes control. The observed reduction in HbA1c should be interpreted cautiously, as the study did not include a non-switching comparator group to determine whether the improvement was attributable to the medication switch or to other clinical factors such as treatment intensification, adherence changes, or routine follow-up.
Ideally, body weight is considered when monitoring the efficacy of diabetes treatment. In this study, body weights were not measured as this variable was not found upon data extraction.
Discussion
This study is concerned with post-marketing clinical practice regarding dosing and blood glucose levels in diabetic patients switching basal insulin treatment from insulin glargine Lantus® to biosimilar insulin glargine Basaglar®. To achieve desired health outcomes, treatment dosing should be transitioned carefully when switching medications [24]. Inefficient medication switch in terms of initiation dose may result in unsuccessful management of diabetes with adverse events such as hyperglycaemia/hypoglycaemia and systemic complications in case of persistent uncontrolled diabetes [4, 26].
Our finding regarding the initiation dose of Basaglar® when switching from Lantus® is in alignment with the guidance for clinical practice [24], as all patients initiated insulin biosimilar Basaglar® with the same dose as the previous Lantus® 100 unit/ mL. Similarly, a study published in 2021 using real-world data to examine the dosing differences in patients switching treatment from Lantus® to Basaglar® has reported no significant difference in the dosing of both medications [31]. On the other hand, another methodologically similar study described the significance between pre-and post-conversion doses; however, it concluded that similar doses are required when converting treatment to Basaglar® with monitoring of blood glucose levels [32]. According to the literature and a medication switch guidance recently published in 2021, there should be no change between the doses if the medication switch is between different insulin glargine 100 units/mL products such as Lantus® and Basaglar® [5, 27, 28].
The study’s results offer a detailed perspective on switching to biosimilar products. Evidence suggests that the switch is generally supported, as reflected by stable or improved HbA1c levels in patients after the switch. The results are consistent with previous real-world studies demonstrating comparable glycaemic outcomes following switching between reference and biosimilar insulin glargine products. Given the established pharmacokinetic and pharmacodynamics equivalence between interchangeable insulin glargine products, the findings align with existing regulatory and clinical evidence. Further research is warranted to investigate the reasons underlying the persistently elevated HbA1c levels observed in this population. The high baseline and post-switch HbA1c values suggest a broader need for treatment intensification strategies, adherence evaluation, and optimization of diabetes management beyond the context of product switching.
Since post-marketing approval of insulin biosimilar, few studies assessing dosing characteristics have described real-world clinical practices and health outcomes. This study is one of few that reflect the practice in Saudi Arabia using real-world data from multi-region healthcare centres. The major limitation of this study was the missing variable of the body weight from the database, which may be due to a lack of follow-up information acquisition by health centres or data records system inefficiency. Furthermore, the total sample size of this study was affected by limited data availability. This may be attributed to several factors, including patient follow-up visitation irregularity/interruptions, healthcare interruptions, management received through other healthcare centres, and medical record system-related errors.
Research Limitations
The study’s non-interventional and retrospective design limits the ability to establish causality. Reliance on existing records can introduce biases if those records are incomplete or inaccurate, complicating the control of potential confounders. Consequently, the results may be influenced by unmeasured variables. A key limitation of this study is the absence of a non-switching comparator group. Without a control group of patients who remained on Lantus®, it is not possible to definitively attribute the observed reduction in HbA1c to the act of switching itself. The modest improvement may reflect regression to the mean, intensified clinical monitoring during follow-up, adherence changes, or routine diabetes management rather than a pharmacological difference between products.
Furthermore, detailed information regarding dose adjustments of basal or short-acting insulins following the switch was not available, limiting insight into treatment intensification strategies. Also, the reasons for alternating between Lantus® and Basaglar® in the second treatment group were not captured in the database, introducing uncertainty into the interpretation of HbA1c outcomes.
Despite body weight importance as a considerable factor in diabetes management, its absence in this dataset is unlikely to directly affect interpretation of switching equivalence but does limit broader metabolic assessment.
Although the sample size of 879 patients is substantial, it may still be insufficient to capture the full variability in clinical practice and patient responses. Additionally, the follow-up period was limited to 6 months post-switch. A larger sample size and extended follow-up period could provide more robust data and a better understanding of long-term outcomes.
As a real-world observational study, the lack of randomization increases the risk of selection bias, affecting the comparability of the groups and the validity of the conclusions drawn.
Furthermore, the study does not account for patient adherence to the prescribed insulin regimen. Variations in adherence can significantly impact HbA1c outcomes and confound the interpretation of the medication switch’s effectiveness. Future research should focus on identifying determinants of persistently poor glycaemic control and strategies for treatment optimization rather than further comparative switching evaluations.
Future Directions
This study revealed that [300 (34%)] of total patients were not completely switched to biosimilar insulin glargine Basaglar® but alternated between Basaglar® and insulin glargine Lantus®. This may have been the case due to drug availability or a treatment choice to achieve preferable health outcomes in terms of side effects and/or blood glucose control. In addition, findings regarding HbAlc levels did not agree with the literature. As a next step, we may further assess confounding factors in this study population that may justify the statistically significant decrease in mean HbAlc levels after the medication switch, as statistical significance may not conclude clinical relevance. Furthermore, longer periods of pre- and post-follow up treatment may be explored.
Conclusion
Switching from Lantus® to biosimilar Basaglar® was implemented according to clinical guidance, maintaining the same insulin concentration at the time of conversion. Glycaemic control remained suboptimal in this cohort both before and after switching, although a modest statistical improvement in HbA1c was observed. These findings support the clinical interchangeability of insulin glargine products in real-world practice. Future research should focus on identifying determinants of persistently poor glycaemic control and strategies for treatment optimization rather than further comparative switching evaluations.
Data availability
The datasets generated and/or analysed during the current study are available in the SFDA database. Data can be provided upon request.
Acknowledgement
We would like to express our sincere gratitude to the Saudi Food and Drug Authority (SFDA) for their support and guidance throughout this research project.
Funding sources
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Author contributions
Salwa Almomen: Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Fares Alrubaish: Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Radwan Hafiz: Writing – review & editing. Ali M Alhomaidan: Writing – review and editing, Methodology, Data curation, Conceptualization, Supervision.
Disclaimer
The views expressed in this paper are those of the authors and do not necessarily reflect those of the Saudi Food and Drug Authority (SFDA) or its stakeholders. Ensuring the accuracy and validity of the data is the sole responsibility of the research team.
Competing interests: The authors of this research paper are currently employed by the Saudi Food and Drug Authority (SFDA), which is the same institution that sponsored and conducted the research. However, the authors have made every effort to maintain objectivity and impartiality in the research and reporting of the findings.
Provenance and peer review: Not commissioned; externally peer reviewed.
Authors
Salwa Almomen, MD, MSc
Fares Alrubaish, PharmD
Radwan Hafiz, PharmD
Ali M Alhomaidan, PhD
Saudi Food and Drug Authority, 3904 Northern Ring Road, Hittin-Riyadh 1351307148, Saudi Arabia
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Author for correspondence: Salwa Almomen, MD, MSc, Saudi Food and Drug Authority, 3904 Northern Ring Road, Hittin-Riyadh 1351307148, Saudi Arabia |
Disclosure of Conflict of Interest Statement is available upon request.
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