Insulin glargine is a long-acting, recombinant human insulin analogue used to manage hyperglycemia in diabetes mellitus. It is a clear, colorless solution for subcutaneous injection. Its unique modification involves the addition of two arginine residues to the B-chain and replacement of asparagine with glycine at position A21, shifting the isoelectric point towards neutral pH. This results in a slow, stable, and prolonged release from the subcutaneous tissue with minimal peak activity, providing a basal insulin profile lasting up to 24 hours or longer. In India, it is available in a concentration of 40 IU/mL (U-40), which is distinct from the more common U-100 concentration used globally, requiring careful attention to syringe compatibility.
Adult: Individualized. Typically initiated at 0.2 to 0.4 IU/kg/day or 10 IU once daily, administered at the same time each day (usually at bedtime). Dose is titrated based on fasting blood glucose (FBG) targets. In Type 2 DM, may be added to existing oral therapy.
Note: FOR U-40 INSULIN: MUST use a U-40 insulin syringe or a pen device specifically designed for U-40 insulin. Administer subcutaneously in the abdominal wall, thigh, or upper arm. Rotate injection sites within the same region to prevent lipodystrophy. Do not dilute or mix with any other insulin or solution. Injection should be at the same time daily.
Insulin glargine binds to the insulin receptor on target cells (primarily liver, muscle, and adipose tissue), initiating a cascade of intracellular signaling events. This promotes cellular glucose uptake, inhibits hepatic glucose production (gluconeogenesis and glycogenolysis), and enhances protein synthesis and lipogenesis while inhibiting lipolysis.
Pregnancy: Pregnancy Category C. Insulin is the drug of choice for glycemic control in pregnancy. Insulin glargine can be used if clearly needed, but human insulin (NPH) is often preferred due to longer safety history. Dose requirements typically increase in second and third trimesters. Close monitoring is essential.
Driving: Patients must be aware of the risk of hypoglycemia which can impair concentration and reaction time. Blood glucose should be checked before and during long drives. Always carry a fast-acting carbohydrate source (glucose tablets) in the vehicle.
| Oral Hypoglycemic Agents (Sulfonylureas, Meglitinides) | Additive hypoglycemic effect, increased risk of hypoglycemia | Major |
| Beta-blockers (e.g., Propranolol) | May mask tachycardia (warning signs) of hypoglycemia; may potentiate or impair glucose recovery | Moderate |
| Thiazide Diuretics, Corticosteroids, Thyroid hormones, Sympathomimetics | May increase blood glucose, requiring insulin dose increase | Moderate |
| ACE Inhibitors, MAO Inhibitors, Octreotide | May enhance hypoglycemic effect | Moderate |
| Alcohol | Potentiates hypoglycemic effect and can impair gluconeogenesis; risk of delayed hypoglycemia | Major |
| Pioglitazone (and other TZDs) | Increased risk of edema and heart failure; monitor for weight gain and edema | Moderate |
Same composition (Insulin Glargine (40IU)), different brands: