How much will 10 units of long-acting (insulin glargine or insulin detemir) insulin lower blood glucose levels throughout the day?

Blood Glucose Reduction with 10 Units of Long-Acting Insulin

There is no fixed, predictable amount that 10 units of long-acting insulin will lower blood glucose throughout the day—the effect varies dramatically based on individual insulin sensitivity, body weight, and baseline glucose levels. However, guideline-based dosing algorithms provide a framework for understanding expected effects.

Understanding Insulin Sensitivity and Expected Effects

The glucose-lowering effect of 10 units of basal insulin depends entirely on your insulin sensitivity factor (ISF), which varies by total daily insulin dose. 1

• For insulin-naive patients with type 2 diabetes, the American Diabetes Association recommends starting doses of 0.1-0.2 units/kg/day, with 10 units being a standard initial dose for patients weighing 50-100 kg 1
• Using the 1500 rule (1500 ÷ total daily dose), a patient on 50 units total daily insulin would expect 1 unit to lower glucose by approximately 30 mg/dL, meaning 10 units could theoretically lower glucose by ~300 mg/dL—but this is NOT how basal insulin works 1

How Basal Insulin Actually Functions

Long-acting insulin (glargine or detemir) provides steady background insulin to suppress hepatic glucose production overnight and between meals, not acute glucose correction. 2, 3

• Insulin glargine provides a peakless, constant effect over 24 hours with delayed onset of action 3
• Nearly 80% of glargine's glucose-lowering effect comes from suppressing endogenous glucose production (EGP) rather than increasing glucose uptake 2
• Glargine reduces morning glucagon levels by approximately one-third compared to NPH insulin, contributing to lower fasting glucose 2

Practical Dosing Framework

The American Diabetes Association uses fasting glucose targets to guide basal insulin titration, not predicted glucose drops per unit. 1

• Target fasting plasma glucose: 80-130 mg/dL 1
• If fasting glucose is 140-179 mg/dL, increase basal insulin by 2 units every 3 days 1
• If fasting glucose is ≥180 mg/dL, increase basal insulin by 4 units every 3 days 1
• This titration approach acknowledges that individual response varies—the goal is reaching target, not predicting exact glucose reduction 1

Weight-Based Dosing Provides Better Context

For hospitalized patients who are insulin-naive or on low-dose insulin, the American Diabetes Association recommends 0.3-0.5 units/kg total daily dose, with half as basal insulin. 1

• For a 70 kg patient: 0.3-0.5 units/kg/day = 21-35 units total daily dose, with 10.5-17.5 units as basal insulin 1
• This suggests 10 units represents approximately 0.14-0.29 units/kg for a 70 kg patient—within the recommended starting range 1

Critical Threshold Considerations

When basal insulin exceeds 0.5 units/kg/day without achieving glycemic targets, the problem is insufficient mealtime coverage, not inadequate basal insulin. 1

• Basal insulin addresses fasting and between-meal glucose levels only 1
• Continuing to escalate basal insulin beyond 0.5-1.0 units/kg/day leads to "overbasalization" with increased hypoglycemia risk and poor postprandial control 1
• At this threshold, add prandial insulin (starting with 4 units before the largest meal) rather than increasing basal insulin further 1

Comparison Between Glargine and Detemir

Glargine and detemir have different potency profiles, with detemir typically requiring higher doses to achieve equivalent effects. 4

• In hospitalized patients, detemir required significantly higher daily doses (0.27 units/kg/day) compared to glargine (0.22 units/kg/day) to achieve similar glycemic control 4
• Both insulins produced mean daily blood glucose of approximately 180-182 mg/dL with equivalent hypoglycemia rates 4
• Detemir should be given twice daily in the majority of type 1 diabetes patients, while glargine is typically once daily 5

Common Pitfalls to Avoid

• Never use basal insulin dose to correct acute hyperglycemia—that's the role of rapid-acting correction insulin 1
• Don't expect immediate glucose reduction—basal insulin has delayed onset and provides steady-state coverage over 24 hours 3
• Avoid assuming linear dose-response relationships—insulin sensitivity varies dramatically between individuals and changes with weight, illness, and activity level 1
• Don't continue escalating basal insulin when fasting glucose is controlled but overall glucose remains elevated—this indicates need for prandial insulin, not more basal insulin 1