What is the appropriate dose of insulin (intramuscular/intravenous medication) for a patient with type 2 diabetes mellitus?

Insulin Dosing for Type 2 Diabetes Mellitus

The recommended starting dose of insulin for patients with type 2 diabetes who are not currently treated with insulin is 0.2 units/kg or up to 10 units once daily of basal insulin. 1

Initial Insulin Therapy

Basal Insulin Initiation

• Start with basal (long-acting) insulin at 0.2 units/kg or up to 10 units once daily, typically administered at the same time each day 1
• Titrate the dose of basal insulin based on fasting fingerstick glucose results over a week 2
• If 50% of fasting fingerstick glucose values are over the goal (90-150 mg/dL), increase dose by 2 units 2, 3
• If more than 2 fasting fingerstick values per week are <80 mg/dL, decrease dose by 2 units 2, 3

Prandial (Mealtime) Insulin Addition

• When basal insulin has been titrated to an acceptable fasting blood glucose but A1C remains above target, consider adding prandial insulin 2
• For individuals advancing to prandial insulin, start with 4 units or 10% of the basal insulin dose at the largest meal or the meal with greatest postprandial excursion 2
• Rapid-acting insulin analogs are preferred for mealtime insulin due to their quick onset of action 2

Premixed Insulin Option

Dosing and Administration

• For patients who may benefit from simpler dosing, premixed insulin products (containing both basal and bolus insulin) can be used 2
• Initiate insulin-naïve patients with 10 units or 0.1-0.2 units/kg of body weight of premixed insulin (e.g., 70/30), typically divided into two daily doses 3
• Administer premixed insulin twice daily, 30 minutes before breakfast and dinner 3
• Adjust doses based on self-monitoring of blood glucose levels, with target fasting blood glucose of 90-150 mg/dL 3

Special Considerations

Dose Adjustments

• Individuals with type 2 diabetes generally require higher daily doses (1 unit/kg) compared to those with type 1 diabetes 2
• Dosage adjustments may be needed with changes in physical activity, meal patterns, during acute illness, or changes in renal or hepatic function 1
• When adding significant prandial insulin doses, particularly with the evening meal, consider decreasing the basal insulin dose 2

Administration Routes

• Administer insulin subcutaneously into the abdominal area, thigh, or deltoid, and rotate injection sites within the same region 1
• The abdomen has the fastest rate of absorption, followed by the arms, thighs, and buttocks 2
• Intramuscular injection is not recommended for routine injections but can be used in certain circumstances (e.g., diabetic ketoacidosis) 2

Monitoring and Safety

Blood Glucose Targets

• Aim for fasting and premeal blood glucose goals of 80-130 mg/dL and two-hour postprandial goals of less than 180 mg/dL 4
• For older adults or those with comorbidities, consider less stringent targets (e.g., 90-150 mg/dL) 2
• Monitor for hypoglycemia, which is the most common adverse effect of insulin therapy 3

Avoiding Complications

• Do not use rapid-acting insulin at bedtime to avoid nocturnal hypoglycemia 3
• During changes to insulin regimen, increase the frequency of blood glucose monitoring 1
• Patients with severe or recurrent hypoglycemia may benefit from temporary relaxation of glycemic targets 4

Common Pitfalls to Avoid

• Failing to adjust basal insulin dose when adding prandial insulin, which can lead to hypoglycemia 2
• Using fixed premixed insulin ratios that may not be optimal for all patients, particularly those with varying insulin requirements throughout the day 3
• Neglecting to rotate injection sites, which can lead to lipohypertrophy and variable insulin absorption 2, 1
• Inadequate monitoring during dose adjustments, which can lead to suboptimal glycemic control or hypoglycemia 1

Remember that insulin dosing must be individualized based on the patient's metabolic needs, blood glucose monitoring results, and glycemic control goals, with dosage adjustments made under medical supervision with appropriate glucose monitoring 1.