Lantus Dosing Calculator

Lantus (insulin glargine) is a long-acting basal insulin analog. It is absorbed slowly from the subcutaneous injection site and provides steady insulin levels for approximately 24 hours. Unlike short-acting insulins that cover meals, basal insulin like Lantus provides the background insulin needed between meals and overnight. It works by lowering blood glucose through increased glucose uptake by cells and decreased glucose production by the liver. Lantus is used in both Type 1 and Type 2 diabetes management.

For Type 1 diabetes, a common starting dose is 0.2-0.3 units per kilogram of body weight per day. For Type 2 diabetes, a standard approach is 10 units once daily, or 0.1-0.2 units/kg/day. The actual starting dose must be individualized by a healthcare provider based on the patient's clinical presentation, glycemic control, and presence of other medical conditions. This calculator provides an educational estimate; prescribers should adjust based on clinical judgment and patient factors.

For most non-pregnant adults with diabetes, the target fasting blood glucose is 80-110 mg/dL according to American Diabetes Association recommendations. Some individuals may have individualized targets set by their healthcare provider. Elderly patients or those with hypoglycemia unawareness may have higher targets (100-130 mg/dL or greater) to reduce hypoglycemia risk. Pregnant women have stricter targets (60-99 mg/dL fasting). Always follow your prescriber's specific glucose targets.

Dose adjustments should typically be made every 3-7 days after observing a pattern of fasting glucose readings. Making changes too frequently can lead to oscillation and poor glycemic control. Guidelines recommend using an average of 2-3 days of fasting glucose readings before adjusting. Each dose change should be 2-4 units for established patients. More frequent or larger adjustments may increase hypoglycemia risk. Always consult your healthcare provider before making changes.

There is no absolute maximum dose of Lantus; doses up to 100+ units daily are used in insulin-resistant patients. However, the practical maximum for a single injection is typically 40 units due to injection volume and subcutaneous absorption constraints. Doses exceeding 40 units should generally be split into two injections (e.g., 25 units in morning, 20 units in evening). Split dosing improves absorption and glucose control. Prescribers adjust doses individually based on patient response.

Lantus should be injected once daily at approximately the same time each day. The time can be in the morning or evening—what matters most is consistency. Because Lantus has a 24-hour duration, it provides steady insulin levels when given at the same time daily. If you need to change your injection time, do so gradually (one hour earlier or later per day) to avoid glucose variability. Always consult your healthcare provider before changing your injection schedule.

Hypoglycemia (low blood sugar) symptoms include shakiness, sweating, rapid heartbeat, anxiety, hunger, tingling around the mouth, and difficulty concentrating. Severe hypoglycemia can cause confusion, loss of consciousness, or seizures. Mild-to-moderate hypoglycemia is treated with 15 grams of fast-acting carbohydrates (juice, glucose tablets, candy). After treating, recheck blood glucose in 15 minutes and repeat if necessary. Carry medical identification and teach family/friends to recognize and treat severe hypoglycemia. Discuss hypoglycemia prevention and glucagon use with your prescriber.

Lantus is administered via subcutaneous injection using a pen device or vial and syringe. Approved injection sites include the abdomen, thighs, and upper arms. Rotate injection sites with each dose to prevent lipohypertrophy (fat lumps). Never inject directly into areas with lumps, hardness, or swelling. Allow insulin to reach room temperature before injecting; cold insulin may be uncomfortable and slower to absorb. Clean skin with an alcohol swab but allow it to dry before injecting. Proper injection technique is essential; ask your healthcare provider or diabetes educator to observe your technique.

The most common side effect of Lantus is hypoglycemia (low blood sugar), especially when combined with rapid-acting insulins or other diabetes medications. Injection site reactions (redness, swelling, itching) occur in some patients but usually resolve with continued use at different injection sites. Weight gain is common with insulin therapy due to improved glucose control and anabolic effects. Rare but serious side effects include allergic reactions (rash, difficulty breathing) and hypokalemia (low potassium). Report any unusual symptoms to your healthcare provider immediately.

Unopened Lantus pens should be stored in a refrigerator at 2-8°C (36-46°F) until the expiration date. Once opened, a Lantus pen can be stored at room temperature (up to 30°C/86°F) for up to 28 days, even if it remains in the refrigerator. Do not freeze Lantus or expose it to direct heat or sunlight, as this destroys the insulin. Always inspect Lantus before use; it should be clear and colorless. If cloudy, frozen, or discolored, discard it. When traveling, use an insulated case to protect insulin from extreme temperatures.