Managing insulin therapy is crucial for the health of approximately 150 to 200 million people worldwide who depend on it daily. However, it can be challenging to handle this treatment, and even minor mistakes can have severe consequences for their health. Such mistakes can make the therapy less effective, leading to high blood sugar levels, discomfort, and other health risks. Whether it’s storing insulin incorrectly, using the wrong doses, or timing injections poorly, these mistakes can disrupt the delicate balance required for effective diabetes management.

In this article, you will learn about ten common ways you might be accidentally disrupting your insulin therapy. We will provide straightforward tips and strategies to help you avoid these pitfalls. 

So, let’s get started!

1. Inconsistent Injection Sites

woman injecting insulin into stomach

Using the same spot repeatedly for insulin injections can lead to problems like poor insulin absorption and the formation of fatty lumps, known as lipohypertrophy. Rotating injection sites is crucial because it helps ensure insulin is properly absorbed into the body. If insulin doesn’t absorb well, it can lead to unstable blood sugar levels. According to a study, about 38.3% of participants had developed lipohypertrophy or other skin issues at their usual injection sites. 

Additionally, 25.4% of the participants admitted they did not always rotate their injection sites. These issues can disrupt effective insulin therapy, leading to fluctuations in blood sugar levels and potentially severe complications over time. Therefore, consistently rotating injection sites is key to effective diabetes management and avoiding complications associated with poor insulin absorption.

2. Irregular Timing of Insulin Doses

Hand drawing a syringe from an insulin vial

Irregular timing of insulin doses can significantly disrupt insulin therapy, leading to poor glycemic control and increased risks of hypoglycemia and weight gain. For basal insulin, which is used to maintain steady glucose levels, it’s crucial to administer it simultaneously each day due to its 24-hour action. A study found that variations in injection times greater than 240 minutes could lead to a higher frequency of hypoglycemic episodes and weight gain. Specifically, about 50% of type 2 diabetes patients reported mistiming their insulin doses by more than 120 minutes, which was associated with these adverse effects.

To ensure consistent timing, setting reminders on the phone or using a dedicated app can help manage insulin administration times. Additionally, establishing a routine linked to daily activities, such as meal times or bedtime, can aid in making insulin injections a regular part of one’s schedule. These strategies are vital for enhancing the effectiveness of insulin therapy and minimizing the risks associated with irregular dosing.

3. Neglecting Blood Sugar Monitoring

Person checking blood sugar levels with glucometer

Neglecting to monitor blood sugar levels when managing insulin doses can significantly disrupt insulin therapy. Adjusting insulin doses accurately to maintain blood sugar within a target range without regular monitoring becomes challenging. This can lead to poor glycemic control, as data shows many patients do not achieve their glycemic targets. For instance, the National Health and Nutrition Examination Survey (NHANES) data indicated that 45% of diabetes patients did not meet the desired glycemic level of less than 7% A1C. 

Regular monitoring helps precisely adjust insulin doses based on real-time glucose levels, potentially reducing the risks of hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar). Tools such as continuous glucose monitors (CGMs) provide continuous insight into glucose levels, allowing for more dynamic and informed adjustments to insulin therapy, ultimately supporting better diabetes management and health outcomes.


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4. Skipping or Delaying Meals

Clock next to empty dinner plate

Skipping or delaying meals can significantly disrupt insulin therapy, especially for those managing diabetes with bolus insulin. When meals are skipped or delayed, the timing of insulin administration can be thrown off, leading to the risk of hypoglycemia (low blood sugar). Bolus insulin is typically administered at mealtime to help manage the rise in blood glucose after eating. 

If you skip a meal but have already administered your insulin, there’s no food to counterbalance the insulin’s effect, potentially causing your blood glucose to drop too low. This misalignment between insulin action and glucose availability from food can be dangerous. A study suggests that inconsistent meal consumption can increase the risk of metabolic disturbances. 

In meal timing and insulin therapy, it’s crucial to maintain a consistent schedule to align insulin administration with food intake to prevent the risk of hypoglycemia. Planning meals can help ensure that the insulin’s peak action coincides with the blood glucose rise after eating, minimizing complications and stabilizing blood sugar levels.

5. Poor Dietary Choices

woman choosing between donuts and apple

Poor dietary choices, especially the consumption of high-sugar and high-carbohydrate foods, can significantly disrupt the effectiveness of insulin therapy for managing type 2 diabetes. Foods high in sugar and refined carbohydrates quickly break down into glucose, leading to rapid spikes in blood sugar levels. This requires the body to use more insulin to manage the increased glucose in the bloodstream. Over time, consistently high blood sugar levels can lead to insulin resistance, where the body’s cells don’t respond effectively to insulin, making blood sugar management even more challenging. 

For instance, studies have shown that diets with high glycemic indexes can increase HbA1c levels, a marker of long-term blood sugar control, compared to diets with lower glycemic indexes. Healthier food choices for individuals on insulin therapy include nutrient-dense, low glycemic index foods such as whole grains, legumes, vegetables, and nuts. These foods break down more slowly, providing a more stable release of glucose into the bloodstream and reducing the immediate demand for insulin, thus supporting more stable blood sugar levels and better overall diabetes management.

6. Inadequate Hydration

Man drinking water from water bottle

Inadequate hydration can significantly impact blood sugar management and insulin efficiency in individuals with diabetes. Water plays a crucial role in maintaining blood sugar levels as it helps dissolve glucose and aids in its transport through the bloodstream to cells. According to a study, blood glucose concentrations can rise when the body is dehydrated, making it more challenging to manage diabetes effectively. 

Additionally, dehydration can affect insulin’s ability to function properly, reducing its effectiveness in lowering blood sugar levels. During hyperglycemic crises, such as diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS), severe dehydration is common due to increased urination caused by high blood sugar levels. This can lead to a vicious cycle where high glucose levels cause more dehydration, and dehydration causes insulin to be less effective, thus worsening the hyperglycemia. 

Regular fluid intake is emphasized as a preventive measure to maintain proper hydration, essential for effective blood sugar and insulin management. This is particularly important in managing acute diabetic complications and preventing hospital admissions related to hyperglycemic crises.

7. Incorrect Insulin Storage

insulin vial and two syringes on table

Incorrect insulin storage significantly disrupts insulin therapy by affecting the medication’s effectiveness and safety. Insulin must be stored within a specific temperature range (2°C to 8°C) to maintain its potency until its expiration date. Insulin can degrade when exposed to temperatures outside this range, such as freezing or heat above 30°C, reducing its effectiveness in controlling blood sugar levels. This can lead to poorly managed diabetes and increased risks of complications. For example, if insulin is frozen, it can become unusable, and if stored at high temperatures, it can lose its efficacy much faster.

To ensure proper insulin storage and preserve its efficacy, insuin pens, cartridges, and vials that are not in use should be stored in a refrigerator at the recommended temperature range. Once an insulin vial is opened, it can generally be kept at room temperature (below 30°C) for up to 4 weeks. It is important to avoid storing insulin in direct sunlight or in a car where temperatures can exceed safe limits.

Insulin should not be stored with the needle attached to avoid clogging and leakage. For those without access to refrigeration, options like storing insulin in a cool, dark place or using innovative solutions like a “zeer pot” — a cooling device made with water or wet sand — can help maintain insulin at a safer temperature. These practices are crucial for maintaining the therapeutic effectiveness of insulin and ensuring safe diabetes management.

8. Forgetting Doses

patient receiving insulin injection into arm

Forgetting or missing insulin doses can significantly disrupt insulin therapy and negatively affect blood sugar control in people with diabetes. Studies have shown that around 20-45% of people report mistiming their insulin doses, and this irregularity is linked to poorer glycemic control. Specifically, those who miss doses often have higher glycated hemoglobin (HbA1c) levels, indicating less stable blood sugar levels over time. 

Missed doses can lead to higher risks of high blood sugar (hyperglycemia) and low blood sugar (hypoglycemia), depending on the timing and amount of the missed insulin. Digital solutions like smartphone apps that send reminders or alarms can be very effective in helping manage and remember insulin administration. These tools help integrate diabetes management into daily routines, reducing the chances of missing or mistiming doses.

9. Smoking Cigarettes

Man lighting cigarette

Smoking can interfere with insulin therapy primarily by making the body less responsive to insulin, a condition known as insulin resistance. Research shows that smokers are generally less sensitive to insulin than non-smokers. This resistance to insulin’s effects means that even when insulin is administered naturally by the body or through injections as part of diabetes treatment, it is less effective at lowering blood sugar levels. 

The study also showed that smokers showed improved insulin sensitivity after quitting for 1 or 2 weeks, indicating that the harmful effects of smoking on insulin function can be reversed somewhat by stopping smoking. Nicotine, a major component of cigarette smoke, is highlighted as a key player in causing this insulin resistance by activating specific cellular pathways that disrupt normal insulin signalling. Therefore, smoking cessation is crucial for improving insulin sensitivity, especially in diabetic patients who rely on insulin therapy to manage their blood sugar levels.

10.  Not Managing Stress and Mental Health

Elderly woman suffering from mental stress

Managing stress and mental health is crucial for effective insulin therapy, particularly in individuals with diabetes. When stress is not managed correctly, it can lead to significant disruptions in insulin signalling and overall glucose management. Chronic stress triggers the release of stress hormones like cortisol, which can directly antagonize insulin’s action, making it less effective at lowering blood sugar levels. This phenomenon increases the risk of insulin resistance, where the body does not respond well to insulin, necessitating higher doses or more frequent insulin administration to achieve the same glucose control.

Research has shown that stressed individuals often have higher fasting plasma insulin levels, a marker of insulin resistance. For instance, a study noted that chronic work stress was positively correlated with insulin resistance. Another study reported that participants exposed to chronic stress had elevated inflammatory markers like TNF- α, associated with insulin resistance. These findings indicate that unmanaged stress complicates insulin therapy by making it less effective and contributes to a cycle of worsening insulin resistance, potentially leading to higher doses of insulin needed and a greater overall burden of disease management for the patient.


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Managing insulin therapy effectively requires awareness and careful attention to the various factors that can disrupt its success. Individuals can better navigate the complexities of insulin therapy by understanding the common pitfalls such as improper storage, inconsistent dosing schedules, and neglecting dietary considerations. Implementing consistent practices and consulting healthcare professionals when needed can significantly improve the outcomes of your treatment plan. Remember, small adjustments can lead to significant improvements in managing diabetes.

FAQs About Insulin Therapy

What is the most common insulin therapy?

The standard and most commonly used strength in the United States today is U-100, which means it has 100 units of insulin per milliliter of fluid. However, U-500 insulin is an option for patients with extreme insulin resistance.

How do I start insulin therapy?

Basal insulin typically begins at a low dose (10 to 20 units) and is then gradually increased to find the appropriate dosage for an individual. Combining treatments (e.g., oral medication with insulin) generally reduces the insulin dose compared to insulin alone.

What are the common complications of insulin therapy?

Hypoglycemia is the most prevalent adverse effect of insulin therapy. Other adverse effects may include weight gain and, rarely, electrolyte imbalances like hypokalemia, particularly when used in conjunction with other medications that cause hypokalemia.

What happens when you have too much insulin in your body?

Excessive insulin in the bloodstream causes cells to absorb more sugar than necessary, reducing blood sugar levels. Hypoglycemia, or low blood sugar, can result from this. The body’s functioning is impaired when blood sugar levels drop too low. Symptoms of an insulin overdose mimic those of hypoglycemia.

When is the best time to take insulin?

Typically, a dose of short-acting insulin is taken around 30 minutes before each meal. Your doctor or diabetes nurse will guide timing, which may vary depending on the brand you use. Find the timing that suits you best and adhere to it as closely as possible.

What are the side effects of insulin therapy?

Side effects of long-acting insulin Brand names: Abasaglar, Lantus, Levemir, Semglee, Toujeo, Tresiba

  • sweating
  • trembling or shaking
  •  anxiety, confusion, or difficulty concentrating
  • fast heartbeat (palpitations)
  • tingling lips
  • changes in vision such as blurred vision
  • dizziness
  • hunger


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Nishimura, A., Harashima, S.-i., Fukushige, H., Inagaki, N., Wang, Y., Liu, Y., & Hosoda, K. (2017). A Large Difference in Dose Timing of Basal Insulin Introduces Risk of Hypoglycemia and Overweight: A Cross-Sectional Study. Diabetes Ther, 8(2), 405–415.

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National Library of Medicine. (2009). Hyperglycemic Crises in Adult Patients With Diabetes. PubMed Central.

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Robinson, S., Newson, R. S., Liao, B., Kennedy-Martin, T., & Battelino, T. (2021). Missed and Mistimed Insulin Doses in People with Diabetes: A Systematic Literature Review. Diabetes Technol Ther, 23(12), 844-856. doi:10.1089/dia.2021.0164

Bergman, B. C., Perreault, L., Hunerdosse, D. M., Kerege, A., Playdon, M. C., Samek, A. M., & Eckel, R. H. (2012). Novel and reversible mechanisms of smoking-induced insulin resistance in humans. Diabetes, 61(12), PMC3501865.

Yaribeygi, H., Maleki, M., Butler, A. E., Jamialahmadi, T., & Sahebkar, A. (2022). Molecular mechanisms linking stress and insulin resistance. EXCLI Journal, 21. PMID: 35368460. PMCID: PMC8971350. doi:10.17179/excli2021-4382