Initiating Insulin Therapy in Type 2 Diabetes

Immediate Insulin Initiation Criteria

Insulin should be initiated immediately at diagnosis when blood glucose is ≥300 mg/dL or HbA1c is ≥10%, especially if the patient has symptoms of hyperglycemia or evidence of catabolism, according to the American Diabetes Association guidelines 1
The American Diabetes Association recommends starting insulin at diagnosis if blood glucose ≥300-350 mg/dL, HbA1c ≥10% (86 mmol/mol), symptomatic hyperglycemia, or evidence of catabolism are present 1, 2
Symptomatic hyperglycemia, including polyuria, polydipsia, nocturia, and weight loss, is an indication for immediate insulin initiation 1, 3

The American Diabetes Association guidelines recommend adding basal insulin when HbA1c remains above target after 3 months on metformin plus one or two additional oral agents 1, 2
Basal insulin should be added when oral agents fail to maintain glycemic control, typically when HbA1c exceeds 7% on maximally tolerated doses, as emphasized by the American Diabetes Association 1, 4

For youth with type 2 diabetes, basal insulin should be started if HbA1c ≥8.5% (69 mmol/mol) with symptoms, while initiating metformin, according to the American Diabetes Association guidelines 3

Initial basal insulin dosing should start with 10 units daily or 0.1-0.2 units/kg, depending on hyperglycemia severity, and titrate by 2-4 units every 3-7 days until fasting glucose reaches target 2, 5
Continuing metformin when adding insulin can reduce insulin requirements and minimize weight gain, as recommended by the American Diabetes Association 1, 4

Insulin therapy can cause weight gain, which can be minimized by continuing metformin and considering addition of GLP-1 receptor agonists or SGLT2 inhibitors, according to the American Diabetes Association guidelines 1, 5