What is the recommended dosage and administration of insulin glargine (insulin glargine) for patients with diabetes?

Insulin Glargine Dosing and Administration

Administer insulin glargine subcutaneously once daily at the same time every day, with starting doses of 0.2 units/kg or up to 10 units daily for insulin-naive type 2 diabetes patients, or approximately one-third of total daily insulin requirements for type 1 diabetes patients (combined with short-acting insulin for the remaining two-thirds). 1

Starting Doses by Diabetes Type

Type 2 Diabetes (Insulin-Naive)

• Start with 0.2 units/kg or up to 10 units once daily 1
• This applies to patients not currently on insulin therapy 2
• Typically added when oral medications fail to achieve glycemic targets 2
• Can be used alone or combined with metformin and possibly one additional non-insulin agent 2

Type 1 Diabetes

• Start with approximately one-third of total daily insulin requirements 1
• Must be used concomitantly with short-acting, premeal insulin to satisfy the remainder of daily insulin needs 1
• Total daily insulin requirements typically range from 0.4 to 1.0 units/kg/day, with 0.5 units/kg/day as a typical starting point in metabolically stable patients 3
• Basal insulin (glargine) typically comprises 40-60% of total daily dose in multiple daily injection regimens 2

Administration Guidelines

Timing and Technique

• Administer at the same time each day to maintain stable blood glucose levels 2, 1
• Can be given at any time of day (morning, evening, or bedtime), but consistency is critical 1
• Inject subcutaneously into the abdomen, thigh, or deltoid 1
• Rotate injection sites within the same region to reduce risk of lipodystrophy and localized cutaneous amyloidosis 1
• Avoid injecting into areas of lipodystrophy, as this can cause hyperglycemia; switching to unaffected areas may cause hypoglycemia requiring close monitoring 1

Critical Administration Restrictions

• Never administer intravenously or via insulin pump 1
• Do not dilute or mix with any other insulin or solution due to the low pH of its diluent 3, 1
• Never share pens, syringes, or needles between patients due to blood-borne pathogen transmission risk 1

Switching from Other Insulins

From NPH Insulin

• Once-daily NPH to once-daily glargine: Use the same dose 1
• Twice-daily NPH to once-daily glargine: Start with 80% of total NPH dose 1, 4
• This dose reduction lowers hypoglycemia risk during the transition 1

From Concentrated Glargine (U-300)

• When switching from once-daily U-300 glargine to U-100 glargine: Start with 80% of the U-300 dose 1

Dose Titration and Monitoring

Titration Strategy

• Individualize dosage based on metabolic needs, blood glucose monitoring results, and glycemic control goals 1
• Target fasting blood glucose <120 mg/dL (6.7 mmol/L) during titration 5
• Increase frequency of blood glucose monitoring during any insulin regimen changes 1
• All dosage adjustments should be made under medical supervision with appropriate glucose monitoring 1

When to Intensify Therapy

• If basal insulin dose exceeds 0.5 units/kg/day and A1C remains above target, consider advancing to combination injectable therapy with GLP-1 receptor agonists or adding prandial insulin 3, 2
• When adding significant prandial insulin doses (especially with evening meal), consider decreasing the basal insulin dose 2
• If A1C is <8% when starting mealtime bolus insulin, consider reducing basal insulin dose 3

Special Considerations for Twice-Daily Dosing

While once-daily dosing is standard, twice-daily glargine may be necessary when once-daily administration fails to provide 24-hour coverage, particularly in:

• Type 1 diabetes patients with persistent glycemic variability 2
• Patients requiring high basal insulin doses that exceed absorption capacity for once-daily administration 2
• Patients with refractory hypoglycemia despite optimized once-daily regimens 2

Important caveat: Before implementing twice-daily glargine, ensure proper once-daily dose titration has been attempted, and consider whether switching to newer ultra-long-acting insulins (U-300 glargine or degludec) might provide more stable 24-hour coverage 2

Clinical Advantages

Pharmacokinetic Profile

• Onset of action approximately 1 hour with a peakless profile 2
• Duration of action up to 24 hours, suitable for once-daily dosing 2, 6, 7
• More consistent absorption than NPH insulin 2

Hypoglycemia Risk

• Significantly reduced risk of nocturnal hypoglycemia compared to NPH insulin 2, 8, 7, 5
• This advantage is particularly pronounced in patients previously on once-daily NPH regimens 8
• Lower overall hypoglycemia rates, especially in the first four weeks after switching 4

Dosage Adjustments Required With

• Changes in physical activity 1
• Changes in meal patterns (macronutrient content or timing) 1
• Acute illness 1
• Changes in renal or hepatic function 1
• Higher doses needed during puberty, pregnancy, and medical illness 3

Common Pitfalls to Avoid

• Failing to maintain consistent daily timing reduces the predictability of glucose control 2
• Injecting repeatedly into areas of lipodystrophy causes erratic insulin absorption and unpredictable glycemic control 1
• Mixing glargine with other insulins alters its pharmacokinetic profile and is contraindicated 3, 1
• Not reducing basal dose when adding prandial insulin increases hypoglycemia risk 3, 2
• Inadequate glucose monitoring during regimen changes may miss hypo- or hyperglycemia 1