Journal of Clinical Diabetes
Open Access

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by insulin resistance and impaired insulin secretion. Over time, individuals with T2DM may experience progressive beta-cell dysfunction, requiring exogenous insulin therapy to maintain glucose control. Basal insulin, a long-acting insulin, is commonly used to mimic the body’s natural insulin secretion, targeting fasting blood glucose levels and minimizing hyperglycemia [1-3].

However, in clinical practice, there is increasing concern about the phenomenon of "insulin overbasalization." This occurs when patients are prescribed basal insulin doses that are higher than necessary to maintain adequate glucose control. Overbasalization can lead to adverse outcomes such as recurrent hypoglycemia, weight gain, insulin resistance, and a compromised quality of life.

This article aims to quantify and characterize insulin overbasalization in a family medicine practice setting, where diabetes management is typically provided in the context of broader primary care. Family medicine practitioners often face the challenge of balancing glycemic control with minimizing the risks of excessive insulin dosing. The discussion highlights the prevalence of insulin overbasalization, contributing factors, clinical consequences, and strategies for optimizing basal insulin use [4,5].

Description

Basal insulin is a long-acting form of insulin used to control blood glucose levels throughout the day, especially overnight and between meals. It is typically administered once or twice daily, depending on the patient’s needs and the type of insulin prescribed. Common types of basal insulin include insulin glargine (Lantus, Toujeo), insulin detemir (Levemir), and insulin degludec (Tresiba). These insulins have a slow onset and provide a steady level of insulin over an extended period.

Basal insulin therapy is generally introduced when patients with T2DM cannot maintain adequate blood glucose levels using oral medications or other injectable therapies. By targeting fasting blood glucose levels, basal insulin helps to control the liver's glucose production, a major contributor to hyperglycemia in T2DM.

Despite its effectiveness in managing fasting glucose levels, basal insulin does not address postprandial (after meal) hyperglycemia, which is another hallmark of T2DM. Consequently, some patients may also require bolus insulin or other agents (such as GLP-1 receptor agonists or SGLT2 inhibitors) to optimize overall glycemic control [6-8].

However, basal insulin use is not without risks. Incorrect dosing, inadequate monitoring, and a lack of individualized care can result in insulin overbasalization, leading to a range of clinical problems, including hypoglycemia, excessive weight gain, and diminished quality of life. This phenomenon is particularly concerning in primary care settings, where individualized treatment plans may not always be implemented effectively.

The prevalence of insulin overbasalization is difficult to quantify precisely due to the variety of factors influencing insulin prescriptions, including clinician experience, patient preferences, and underlying comorbidities. However, several studies have suggested that insulin overbasalization is more common than previously recognized.

In a typical family medicine practice, patients with T2DM may present with uncontrolled blood glucose levels despite being on basal insulin. This is often attributed to overbasalization—patients receiving insulin doses higher than necessary. Overbasalization can occur when physicians adjust basal insulin doses based on fasting glucose levels alone, without considering the overall insulin needs, including mealtime insulin or lifestyle factors. In the absence of comprehensive monitoring, this can lead to excessive basal insulin dosing and poor outcomes.

While there is no single definition of overbasalization, some criteria can help clinicians identify patients at risk. These include:

To quantify overbasalization, clinicians often use metrics such as total daily insulin dose (TDD) or basal-to-bolus insulin ratios. Studies have shown that a basal insulin dose exceeding 50% of the TDD may indicate overbasalization, although this can vary depending on the patient’s specific needs and treatment plan [9,10].

Discussion

Several factors contribute to insulin overbasalization, both at the level of the healthcare provider and the patient. Understanding these factors can help reduce the likelihood of overbasalization and improve patient outcomes. In family medicine practices, patients with T2DM may receive limited monitoring of their insulin therapy. Without regular blood glucose checks, continuous glucose monitoring (CGM), or HbA1c assessments, healthcare providers may make suboptimal dosing decisions based on incomplete data. For example, adjusting basal insulin solely based on fasting glucose measurements without considering postprandial glucose levels or overall insulin
There is increasing pressure to achieve tight glycemic control, particularly with the goal of maintaining an HbA1c level below 7%. However, this goal may not always be appropriate for all patients, particularly older adults or those with comorbid conditions. Clinicians may inadvertently overbasalize insulin to meet these aggressive targets, putting patients at risk for hypoglycemia and other adverse outcomes.

Patients who lack adequate understanding of basal insulin’s role in diabetes management may be more likely to mismanage their insulin regimen. Without proper education, patients may increase their basal insulin doses in response to perceived high blood glucose, leading to overbasalization. Certain patient characteristics, such as a history of insulin resistance, body mass index (BMI), or concurrent medications, can influence insulin needs. Patients with higher BMI or metabolic syndrome may require higher doses of insulin, but they are also more prone to insulin resistance. In these cases, overbasalization can lead to weight gain and worsening insulin resistance.

Insulin is a hormone that promotes fat storage. Excessive insulin doses can result in weight gain, which is a common side effect of insulin therapy. Weight gain can exacerbate insulin resistance, further complicating diabetes management. In the context of overbasalization, patients may experience unwanted weight gain despite dietary efforts to control their condition.

Ironically, overbasalization can worsen insulin resistance. When insulin levels are too high, the body may become less sensitive to insulin, necessitating even higher doses to achieve the same effect. This can create a vicious cycle where increasing doses of insulin lead to worsening insulin resistance, making it harder for patients to achieve glycemic control.

Hypoglycemia, weight gain, and the physical discomfort associated with excessive insulin doses can negatively impact a patient’s quality of life. Patients may feel frustrated or overwhelmed by their diabetes management, leading to disengagement from their treatment plan and reduced adherence.

Conclusion

Insulin overbasalization is a significant concern in the management of type 2 diabetes, particularly in family medicine practices where patients often present with a variety of chronic conditions. This phenomenon is associated with adverse clinical outcomes, including hypoglycemia, weight gain, insulin resistance, and diminished quality of life. Quantifying and characterizing the presence of overbasalization is essential for optimizing diabetes care.

Key factors contributing to insulin overbasalization include lack of comprehensive monitoring, aggressive treatment goals, inadequate patient education, and clinical practice guidelines that do not always account for individual variability in insulin sensitivity. To address these challenges, healthcare providers should prioritize individualized treatment plans that incorporate regular glucose monitoring, patient education, and a more nuanced approach to insulin dosing.

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