Long-Acting Analog Insulins Dominate the Market
Among the various classes of insulin, long-acting (basal) analog insulins are the most widely used. These modern insulins are designed to provide a steady, peakless supply of insulin over an extended period, typically up to 24 hours or more. This mimics the natural, background insulin production of a healthy pancreas, helping to maintain consistent blood sugar levels between meals and overnight. For many individuals, this predictable action simplifies their treatment regimen and reduces the risk of nocturnal hypoglycemia (low blood sugar), which can occur with older, intermediate-acting insulins.
Insulin Glargine: The Leading Long-Acting Choice
Within the long-acting category, insulin glargine is the most prescribed long-acting insulin in the US market. Marketed under brand names such as Lantus, Basaglar, and Toujeo, insulin glargine consistently represents about half of all insulin treatment visits. Its popularity is due to its reliable, once-daily dosing and well-established safety and efficacy profile. Insulin degludec (Tresiba) is another popular ultra-long-acting option that lasts up to 42 hours, offering even greater dosing flexibility for some patients. The widespread use of these long-acting analogs is a key factor in improving glycemic control for both type 1 and type 2 diabetes.
The Role of Rapid-Acting Insulin
While long-acting insulin provides the basal coverage, rapid-acting insulins are essential for managing blood sugar spikes that occur after meals. Known as bolus or mealtime insulin, these insulins have a rapid onset and short duration of action. The two most commonly used rapid-acting insulins are insulin lispro (Humalog) and insulin aspart (NovoLog). They are typically taken just before or after a meal and are crucial for individuals with type 1 diabetes, who need both basal and bolus insulin, as well as many with type 2 diabetes.
Combination Therapy: Basal and Bolus
For many people with diabetes, a combination therapy known as a basal-bolus regimen is the standard of care. This approach provides the best possible glycemic control by using:
- A long-acting or ultra-long-acting insulin once or twice daily for background insulin.
- A rapid-acting insulin before each meal to manage post-meal glucose spikes.
This regimen offers the highest level of control but requires more frequent injections throughout the day. It is particularly common for those with type 1 diabetes and for many who use insulin pumps.
The Shift to Analog Insulins and Biosimilars
Over the last two decades, there has been a significant shift from older human insulins (like NPH and regular insulin) to newer analog insulins. Analog insulins are genetically engineered to have more predictable action profiles, which leads to better patient outcomes and a lower risk of hypoglycemia.
More recently, the landscape has been shaped by the introduction of biosimilar insulins, which are highly similar to their reference products in terms of safety, purity, and potency. In early 2025, the FDA approved Merilog (insulin-aspart-szjj), the first rapid-acting insulin biosimilar to Novolog (insulin aspart), further increasing access to treatment options. This follows the approval of biosimilar versions of insulin glargine (e.g., Semglee and Rezvoglar) in 2021.
Future Trends: Once-Weekly and Smart Devices
Innovative treatments continue to be developed to reduce the daily burden of injections. Once-weekly insulin icodec is a promising new ultra-long-acting basal insulin. It is currently approved in several countries and undergoing FDA review for potential approval in the US, which would be a significant advancement for patient convenience. Combined with advances in continuous glucose monitoring (CGM) and smart insulin pens, this once-weekly option has the potential to simplify diabetes management further.
Comparison of Insulin Types
| Type | Examples (Brand) | Onset | Peak | Duration | Common Use | Appearance |
|---|---|---|---|---|---|---|
| Rapid-Acting Analog | Lispro (Humalog), Aspart (NovoLog), Glulisine (Apidra) | 10–30 minutes | 30 min–3 hrs | 3–5 hours | Mealtime (bolus) | Clear |
| Short-Acting (Regular) | Humulin R, Novolin R | 30–60 minutes | 2–4 hours | 5–8 hours | Mealtime (bolus) | Clear |
| Intermediate-Acting | NPH (Humulin N, Novolin N) | 1–3 hours | 4–12 hours | 12–18 hours | Background (basal) | Cloudy |
| Long-Acting Analog | Glargine (Lantus, Basaglar), Detemir (Levemir) | 1–2 hours | Minimal/No peak | Up to 24 hours | Background (basal) | Clear |
| Ultra-Long-Acting | Degludec (Tresiba), Glargine U-300 (Toujeo) | 1–6 hours | No peak | 36–42 hours | Background (basal) | Clear |
| Premixed | Novolog Mix 70/30, Humalog Mix 75/25 | Varies | Dual peaks | 10–16 hours | Convenience | Cloudy |
Conclusion: Selecting the Right Insulin
The most commonly used insulin type is long-acting analog insulin, with glargine being the market leader. However, diabetes management is not a one-size-fits-all approach. For those with type 1 diabetes, a basal-bolus regimen combining long-acting and rapid-acting insulin is standard practice. For many with type 2 diabetes, long-acting insulin alone or in combination with other medications may suffice. The increasing availability of biosimilars is making these effective treatments more accessible, while innovations like once-weekly insulin offer the promise of even more simplified care in the future. The best insulin choice depends on an individual's specific needs and lifestyle, and it is crucial to work with a healthcare provider to determine the most effective regimen.
This content is for informational purposes only and does not constitute medical advice. Consult with a qualified healthcare professional for personalized medical guidance.
