What is the recommended approach for initiating insulin therapy in a newly diagnosed type 1 diabetes mellitus (T1DM) patient?

Initiating Insulin in Newly Diagnosed Type 1 Diabetes

Most people with newly diagnosed type 1 diabetes should be started on multiple daily injections (MDI) consisting of 3-4 injections per day of basal and prandial insulin, using insulin analogs rather than human insulin to reduce hypoglycemia risk. 1

Initial Insulin Regimen

Start with approximately one-third of total daily insulin requirements as basal insulin, with the remaining two-thirds covered by rapid-acting prandial insulin before meals. 2

• Basal insulin: Use long-acting insulin analogs (such as glargine or detemir) given once daily at the same time each day 1, 2
• Prandial insulin: Use rapid-acting insulin analogs (aspart, lispro, or glulisine) administered 0-15 minutes before each meal 3, 4
• The total starting dose is typically calculated based on weight and metabolic needs, with basal insulin providing continuous background coverage and prandial insulin addressing meal-related glucose excursions 1, 2

Why Insulin Analogs Over Human Insulin

Insulin analogs are strongly preferred because they provide equivalent A1C lowering compared to human insulin but with significantly less hypoglycemia, particularly nocturnal hypoglycemia. 1, 5

• The DCCT trial, which used human insulins, showed intensive therapy reduced microvascular complications but resulted in 62 severe hypoglycemia episodes per 100 patient-years 1
• Modern insulin analogs have more physiologic pharmacokinetic profiles that reduce this hypoglycemia burden while maintaining glycemic control 1, 5

Alternative: Continuous Subcutaneous Insulin Infusion (CSII)

Insulin pump therapy (CSII) is an equally effective alternative to MDI, with no systematic differences in A1C or severe hypoglycemia rates between the two approaches. 1

• Consider CSII for patients with frequent hypoglycemia, hypoglycemia unawareness, or pronounced dawn phenomenon 4
• Sensor-augmented pumps with threshold suspend features can reduce nocturnal hypoglycemia without increasing A1C 1
• The choice between MDI and CSII should be based on patient preference, lifestyle needs, and resource availability 1, 4

Essential Patient Education Components

All patients must be educated on matching prandial insulin doses to three key factors: carbohydrate intake, premeal blood glucose level, and anticipated physical activity. 1

• Carbohydrate counting is the cornerstone skill that enables flexible insulin dosing 1, 3
• Patients should perform frequent blood glucose monitoring, particularly during the initial titration phase 3, 6
• Education on recognizing and treating hypoglycemia is critical given the intensive nature of the regimen 6

Glycemic Targets

Target an A1C less than 7% for most nonpregnant adults with type 1 diabetes to reduce microvascular and macrovascular complications. 6, 4

• Fasting plasma glucose should be 80-130 mg/dL 2
• Postprandial glucose should be less than 180 mg/dL 1
• These targets balance complication prevention against hypoglycemia risk 6

Critical Pitfalls to Avoid

Never use basal insulin alone in type 1 diabetes—prandial insulin coverage is mandatory because these patients have absolute insulin deficiency. 2

• Avoid injecting into areas of lipodystrophy or localized cutaneous amyloidosis, as this causes erratic absorption and hyperglycemia 2
• Rotate injection sites within the same anatomic region (abdomen, thigh, or deltoid) to prevent lipodystrophy 2
• Do not dilute, mix, or administer insulin glargine intravenously or via insulin pump 2
• Increase blood glucose monitoring frequency during any insulin regimen changes to detect hypo- or hyperglycemia early 2

Monitoring and Titration

Adjust insulin doses based on frequent blood glucose monitoring, with fasting values used to titrate basal insulin and pre/postprandial values used to adjust prandial doses. 3, 4

• Continuous glucose monitoring may improve glycemic control regardless of whether MDI or CSII is used 4
• Make dosage adjustments only under medical supervision, particularly when physical activity patterns, meal timing, or illness occurs 2