Why do Type 1 Diabetes Mellitus (T1DM) patients only receive basal insulin at night?

From the Guidelines

T1DM patients may receive only basal insulin at night as part of a basal-only therapy approach, which is typically used in specific situations such as newly diagnosed patients or those with very low insulin requirements. This approach is based on the principle that basal insulin helps control overnight blood glucose and fasting morning glucose levels by suppressing hepatic glucose production during the night when insulin needs are relatively stable 1. The use of basal insulin alone can be an effective way to manage blood glucose levels in certain situations, and common basal insulins used for this purpose include insulin glargine, insulin detemir, or insulin degludec, typically administered once daily at bedtime. Some key points to consider when using basal insulin alone include:

• The principal action of basal insulin is to restrain hepatic glucose production and limit hyperglycemia overnight and between meals 1
• Attainment of fasting glucose goals can be achieved with human NPH insulin or a long-acting insulin analog 1
• Longer-acting basal analogs, such as U-300 glargine or degludec, may convey a lower nocturnal hypoglycemia risk than U-100 glargine 1 However, it is essential to note that this approach is not the standard comprehensive treatment for most T1DM patients, who typically require both basal insulin to cover background insulin needs and bolus insulin to cover meals and correct high blood glucose levels throughout the day. The basal-only approach should be closely monitored, as most T1DM patients will eventually need a full basal-bolus regimen to maintain optimal glycemic control as their disease progresses. Additionally, clinicians should be aware of the potential for overbasalization with insulin therapy, which can mask insufficient mealtime insulin, and clinical signals such as high bedtime-to-morning or preprandial-to-postprandial glucose differential, hypoglycemia, and high glucose variability should prompt evaluation for overbasalization 1.

From the FDA Drug Label

In two clinical studies (Studies A and B), adult patients with type 1 diabetes (Study A, n=585, Study B n=534) were randomized to 28 weeks of basal-bolus treatment with Insulin Glargine or NPH insulin. Regular human insulin was administered before each meal Insulin Glargine was administered at bedtime. In another clinical study (Study C), patients with type 1 diabetes (n=619) were randomized to 16 weeks of basal-bolus treatment with Insulin Glargine or NPH insulin. Insulin lispro was used before each meal. Insulin Glargine was administered once daily at bedtime and NPH insulin was administered once or twice daily. In a randomized, controlled clinical study (Study D), pediatric patients (age range 6 to 15 years) with type 1 diabetes (n=349) were treated for 28 weeks with a basal-bolus insulin regimen where regular human insulin was used before each meal. Insulin Glargine was administered once daily at bedtime and NPH insulin was administered once or twice daily.

T1DM patients may only get basal insulin at night because basal insulin is designed to provide a steady, background level of insulin throughout the day, and administering it at bedtime can help to mimic the body's natural insulin production during sleep. The clinical studies 2 have shown that administering Insulin Glargine at bedtime can be an effective way to manage blood sugar levels in patients with type 1 diabetes.

• Key points:
  • Basal insulin is administered at bedtime to provide a steady background level of insulin
  • This can help to mimic the body's natural insulin production during sleep
  • Clinical studies have shown that administering Insulin Glargine at bedtime can be effective in managing blood sugar levels in patients with type 1 diabetes

From the Research

Basal Insulin Administration in T1DM Patients

• T1DM patients may receive basal insulin at night to mimic the natural physiological secretion of insulin by the pancreas, which helps to restrain the release of glucose from the liver and free fatty acids from adipose tissue, thus preventing hyperglycemia and ketosis 3.
• The administration of basal insulin at night can help to reduce the risk of nocturnal hypoglycemia and fasting hyperglycemia, which can occur with earlier peak effects and shorter duration of action of traditional insulin preparations such as NPH 3.
• Long-acting insulin analogs such as glargine and detemir, which have a longer duration of action and a reduced peak profile, are preferred for basal insulin replacement in T1DM patients, as they can provide a more stable and consistent insulin supply throughout the night 3, 4.
• Continuous subcutaneous insulin infusion (CSII) is also an effective option for basal insulin replacement, as it can provide a more precise and flexible insulin delivery, and can be adjusted to individual patient needs 3, 5.

Clinical Considerations

• The choice of basal insulin regimen should be individualized based on patient factors such as glycemic control, lifestyle, and personal preferences 4, 6.
• The dosage of basal insulin should be adjusted to achieve optimal glycemic control, with a recommended percentage of total daily insulin dose ranging from 30% to 50% 6.
• Regular monitoring of blood glucose levels and adjustment of basal insulin doses as needed can help to optimize glycemic control and reduce the risk of hypoglycemia and other complications 4, 6.