At what point should insulin therapy be initiated in patients with diabetes, and which type of insulin is most appropriate?

From the Guidelines

Insulin therapy should be initiated in patients with type 2 diabetes when oral medications and lifestyle changes fail to maintain adequate blood glucose control, typically when HbA1c remains above 7-7.5% despite other treatments, and the most appropriate type of insulin to start with is basal insulin, beginning with a dose of 10 units or 0.1-0.2 units/kg/day, as recommended by the American Diabetes Association standards of medical care in diabetes 1.

Key Considerations for Insulin Initiation

• The decision to start insulin therapy should be based on the patient's individual needs and circumstances, taking into account their medical history, lifestyle, and preferences.
• Cost considerations are important when selecting an insulin product, and intermediate-acting insulin (neutral protamine Hagedorn [NPH]) may be a more affordable option for some patients 1.
• The goal of insulin therapy is to achieve and maintain optimal blood glucose control, which can help prevent long-term complications such as nerve, kidney, and eye damage.

Insulin Regimens

• For type 2 diabetes, treatment often begins with a single daily injection of basal insulin, which can be titrated upward by 10% to 15%, or 2 to 4 units, once or twice weekly until fasting glucose targets are reached 1.
• If mealtime glucose control is needed, rapid-acting insulin can be added before meals, with a recommended starting dose of 4 U per meal, 0.1 U/kg per meal, or 10% of the basal insulin dose per meal if the HbA1c level is less than 8% 1.
• Premixed insulins (like 70/30 or 75/25 mixtures of intermediate and rapid-acting insulins) are sometimes used twice daily for patients who need a simpler regimen.

Monitoring and Adjustment

• Regular blood glucose monitoring is essential to adjust insulin dosing and ensure optimal blood glucose control.
• Patients should be empowered with self-titration algorithms based on self-monitoring to improve glucose control 1.
• Providers should consider decreasing the basal insulin dose by the same amount of the starting mealtime dose when adding premeal insulin to the regimen 1.

From the FDA Drug Label

1. 3 Initiation of Insulin Glargine Therapy Recommended Starting Dosage in Patients with Type 1 Diabetes The recommended starting dosage of Insulin Glargine in patients with type 1 diabetes is approximately one-third of the total daily insulin requirements. Recommended Starting Dosage in Patients with Type 2 Diabetes The recommended starting dosage of Insulin Glargine in patients with type 2 diabetes who are not currently treated with insulin is 0.2 units/kg or up to 10 units once daily.

Insulin therapy should be initiated in patients with diabetes when their metabolic needs, blood glucose monitoring results, and glycemic control goals indicate the need for insulin.

• For patients with type 1 diabetes, insulin therapy should be initiated with a recommended starting dosage of Insulin Glargine of approximately one-third of the total daily insulin requirements, along with short-acting, premeal insulin to satisfy the remainder of the daily insulin requirements.
• For patients with type 2 diabetes who are not currently treated with insulin, the recommended starting dosage of Insulin Glargine is 0.2 units/kg or up to 10 units once daily. The most appropriate type of insulin is Insulin Glargine, which is a long-acting insulin analog, as it is indicated to improve glycemic control in adult and pediatric patients with diabetes mellitus 2.

From the Research

Initiation of Insulin Therapy

• Insulin therapy should be initiated in patients with type 1 diabetes immediately after diagnosis, typically with multiple daily injections of short-acting or rapid-acting insulin analogue and one or more daily separate injections of intermediate or long-acting insulin 3.
• In patients with type 2 diabetes, insulin therapy should be considered when HbA1c is ≥ 7.5% (≥ 58 mmol/mol) and other treatments have been optimally used 3.
• The preferred method of insulin initiation in type 2 diabetes is to begin by adding a long-acting (basal) insulin or once-daily premixed/co-formulation insulin, alone or in combination with other oral antidiabetic drugs 3.

Choice of Insulin Type

• Rapid-acting insulin analogues, such as faster insulin aspart and ultrarapid-acting lispro, are safe and efficient in controlling postprandial plasma glucose levels without increasing hypoglycaemia 4.
• Long-acting insulin analogues, such as insulin glargine U300 and degludec, have proven to be efficient in reducing hypoglycaemic events due to a more stable action profile 4.
• Insulin glargine is a preferred choice for basal insulin replacement due to its flat, peakless, and long-lasting action profile, which closely reproduces the pharmacokinetics and pharmacodynamics of continuous subcutaneous insulin infusion 5.
• NPH insulin is not recommended for patients with type 1 diabetes and patients with type 2 diabetes who require continuous basal coverage due to its peak action profile and short duration of action 6.

Insulin Regimen

• An insulin regimen should be adopted and individualized to closely resemble a natural physiologic state and avoid wide fluctuating glucose levels 3.
• Blood glucose monitoring is an integral part of effective insulin therapy and should not be omitted in the patient's care plan 3.
• Fasting plasma glucose values should be used to titrate basal insulin, whereas both fasting plasma glucose and postprandial glucose values should be used to titrate mealtime insulin 3.