What are the primary treatment approaches for type 1 vs type 2 diabetes?

Treatment of Type 1 vs Type 2 Diabetes

Type 1 Diabetes: Insulin is Mandatory and Non-Negotiable

All patients with type 1 diabetes require immediate insulin therapy using either multiple daily injections (3-4 injections per day of basal and prandial insulin) or continuous subcutaneous insulin infusion via pump, with insulin analogs strongly preferred over human insulins to reduce hypoglycemia risk 1, 2, 3.

Core Treatment Algorithm for Type 1 Diabetes

Initial Insulin Dosing:

• Start with 0.5 units/kg/day total daily insulin dose in metabolically stable patients 2, 4
• Split approximately 50% as basal insulin and 50% as prandial insulin 2, 4
• Higher doses (up to 1.0 units/kg/day) are required during puberty, pregnancy, or acute illness 2, 4

Insulin Selection:

• Use rapid-acting insulin analogs (aspart, lispro, or glulisine) for prandial coverage rather than regular human insulin 2, 5, 6
• Use long-acting basal analogs (glargine, degludec) over NPH insulin due to reduced hypoglycemia risk and more stable pharmacokinetics 3, 5, 6

Delivery Method Decision Tree:

• First-line: Multiple daily injections (MDI) with basal-bolus regimen 1, 3
• Consider insulin pump (CSII) if: not meeting glycemic targets, experiencing frequent/severe hypoglycemia, or pronounced dawn phenomenon 3, 7
• Consider automated insulin delivery systems for all adults to improve glycemic control and reduce hypoglycemia 2, 3

Essential Patient Education Requirements

Every type 1 diabetes patient must be educated on 1, 2:

• Matching prandial insulin doses to carbohydrate intake using carbohydrate counting
• Adjusting for premeal blood glucose levels
• Modifying doses based on anticipated physical activity
• Calculating correction doses based on concurrent glycemia

Critical Safety Measures:

• All patients must be prescribed glucagon with family/caregivers trained on administration 2
• Continuous glucose monitoring should be standard of care for most patients 3

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Type 2 Diabetes: Stepwise Approach Starting with Non-Insulin Therapy

Metformin is the preferred initial pharmacological agent for type 2 diabetes, combined with lifestyle modifications (weight loss, exercise), unless contraindicated or not tolerated 1.

Treatment Algorithm for Type 2 Diabetes

Step 1: Initial Therapy

• Begin with lifestyle changes (weight loss education, exercise counseling) 1
• Add metformin monotherapy at or soon after diagnosis unless contraindications exist 1

Step 2: When to Add Insulin

• Consider insulin therapy immediately in patients with markedly symptomatic presentation and/or elevated blood glucose levels or A1C 1
• Insulin is essential when A1C ≥10% (≥86 mmol/mol) despite optimal use of diet, physical activity, and other antihyperglycemic agents 8
• Insulin should be considered when A1C is ≥7.5% (≥58 mmol/mol) and glycemic goals are not met 8

Step 3: Insulin Initiation Method

• Preferred approach: Begin by adding long-acting (basal) insulin once daily 8
• Alternative: Once-daily premixed insulin or twice-daily premixed insulin 8
• Can combine with: GLP-1 receptor agonists or continue oral antidiabetic drugs 8
• Do not abruptly discontinue oral medications when starting insulin due to rebound hyperglycemia risk 8

Step 4: Intensification if Needed

• If glucose targets not met with basal insulin, add rapid-acting or short-acting (bolus/prandial) insulin at mealtimes 8

Key Combination Therapy Consideration

Metformin combined with insulin is associated with decreased weight gain, lower insulin dose requirements, and less hypoglycemia compared to insulin alone 8.

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Critical Distinctions Between Type 1 and Type 2 Diabetes Treatment

Fundamental Difference in Pathophysiology Drives Treatment

Type 1 diabetes:

• Absolute insulin deficiency requiring immediate and lifelong insulin replacement 1, 3
• No role for oral antidiabetic medications as primary therapy 1
• Insulin therapy is non-negotiable from diagnosis 8

Type 2 diabetes:

• Progressive insulin resistance and relative insulin deficiency 1
• Initial treatment focuses on lifestyle modification and metformin 1
• Insulin becomes necessary only when other therapies fail or in specific clinical situations 8

Common Pitfall to Avoid

Never delay insulin therapy in type 1 diabetes attempting to use oral medications—this is a life-threatening error. Type 1 diabetes requires insulin from the moment of diagnosis 8. In contrast, never rush to insulin in type 2 diabetes without first optimizing lifestyle modifications and metformin therapy, unless the patient presents with severe hyperglycemia or symptoms 1.

Glycemic Targets

Both types: Target A1C <7% (53 mmol/mol) for most nonpregnant adults 3, 6, though this should account for hypoglycemia risk and individual patient factors.