Determining the correct insulin dosages, whether administered by injection or insulin pump, is a straightforward 3-step procedure. Let's start with these three steps as the basic framework:
1. Determine your basal rates. Your basal rate(s) is defined as the amount of insulin you must take in order to keep your blood sugars stable if you don't eat anything, don't do any strenuous exercise and don't become ill. For example, if your blood sugar is 100 mg/dl right now and don't eat, exercise or become ill, your blood sugar shouldl stay at 100 mg/dl without rising or falling with no peaks or valleys if your basal dosage (Lantus) is correct. All Type 1 diabetic require some basal amount of insulin.
In your case, since you are not on a pump, your long-acting Lantus dose is intended to serve the purpose of your basal rate. How would you know if the 42 units of Lantus you take at dinnertime is the correct dose? One way is you could fast completely and check your blood sugars every hour or so for 24 hours straight. You might consider this a huge sacrifice. The other easier way is to individually check particular time periods like overnight, morning or afternoon separately. In order to do this you should wait five hours after eating any meal or snack and taking any fast-acting insulin (Novorapid) before the particular time period.
Many people like to do the overnight period first, so do it something like this. Take your lunchtime Novorapid and eat lunch at 12-1 o'clock. Now, you are not going to eat anything else or take anymore Novorapid for the rest of the day before bed. You are, however, going to take your 42 units of Lantus at the usual time. You should only conduct this experiment, however if your blood sugar when you take the Lantus is in a somewhat normal range, say 120-160 mg/DL. (If it's too low you could have a hypo reaction while you sleep.)
After you've taken your Lantus start testing and recording your blood sugars every 2-3 hours until you wake up and are ready to have breakfast. The purpose of all this is to see how you blood sugars behave with no food or exercise and only your Lantus. You will be doing this for different periods of your 24-hour day. Then you can make adjustments. (I am not a doctor, but I can help you.) Let's stop here.
Just in case you're wondering, however, here are the next two main steps.
2. Determine your insulin-to-carb ratio. This is how many grams of carbohydates in food you can eat for each unit of fast-acting insulin (Novorapid) you take before a meal. What you have been doing up to now is backwards. You DON't take the same amount of insulin before each meal and then eat enough carbs to accommodate the dose. Instead, you determine by looking at the nutritional information of each food you plan to eat, how many carbs are in that food and your entire meal. Then you calculate your dosage by dividing the total carbs by your carb ratio. It does take some experimentation.
3. Determine your "coverage," that is how much fast-acting insulin you have to take to "cover" a high blood sugar. Determine how many grams of carbs you have to eat to "cover" a low blood sugar. (This is the easiest step.)
Please let me know if you have any questions so far.