What is the difference between long-acting and short-acting insulin?

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Last updated: April 24, 2025View editorial policy

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From the Guidelines

Long-acting insulins, such as glargine or degludec, are preferred over NPH insulin for basal insulin therapy due to their lower risk of hypoglycemia, as demonstrated in recent studies 1. When considering insulin therapy, it's essential to understand the role of both long-acting and short-acting insulins in managing blood glucose levels.

  • Long-acting insulins, also known as basal insulins, provide a steady background insulin level for 12-42 hours, controlling blood glucose between meals and overnight.
  • Short-acting insulins, including rapid-acting analogs and regular insulin, manage blood glucose spikes after meals. The choice between different types of insulin depends on individual factors, including the type of diabetes, lifestyle, and personal preferences. According to recent guidelines 1, basal insulin alone is the most convenient initial insulin regimen and can be added to metformin and other oral agents, with starting doses estimated based on body weight and the degree of hyperglycemia. The use of long-acting basal analogs, such as U-100 glargine or detemir, has been shown to reduce the risk of symptomatic and nocturnal hypoglycemia compared with NPH insulin 1. However, it's crucial to consider the cost differences and individualize treatment based on patient needs and response to therapy, as noted in previous studies 1. In clinical practice, the goal is to achieve optimal glucose control while minimizing the risk of hypoglycemia and other adverse effects, and long-acting insulins, such as glargine or degludec, are often the preferred choice for basal insulin therapy 1.

From the Research

Long-Acting Insulin

  • Insulin glargine is a long-acting insulin analogue with a longer duration of action and a flatter time-action profile compared to NPH insulin 2.
  • It provides a fairly constant, basal insulin supply without peaks in plasma insulin levels for approximately 24 hours, similar to that achieved by a continuous subcutaneous insulin infusion 3.
  • Long-acting insulin analogs, such as glargine and detemir, have improved pharmacokinetic/pharmacodynamic profiles and can be used together in basal-bolus therapy to more closely mimic physiologic insulin secretion patterns 4.

Short-Acting Insulin

  • Rapid-acting insulin analogs, such as aspart, lispro, and glulisine, have improved pharmacokinetic/pharmacodynamic profiles and can be used to control postprandial plasma glucose 4.
  • The addition of a short- or rapid-acting insulin may be needed prior to meals (basal-prandial approach) if glycemic control is not achieved with basal insulin alone 5.

Comparison of Long-Acting and Short-Acting Insulin

  • Insulin glargine has been shown to reduce nocturnal hypoglycaemia and improve dinner-time glucose control compared to NPH insulin 2, 3.
  • The choice of insulin therapy should be guided by a patient's baseline glycosylated hemoglobin (A1C), age, lifestyle, competence, personal preferences, and comorbidities 5.
  • Newer formulations of basal insulins, such as degludec and glargine U-300, offer options that may overcome barriers to insulin use, including the high risk of hypoglycemia and glycemic variability 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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