Continue to check your blood sugar 2 hours after meals and in the middle of the night once a month to be certain that you are not having unexpected high blood sugars at these times. Because the time between lunch and supper can often be 6 or 7 hours, it is not surprising that your lunchtime insulin is wearing off before supper. You should be able to make adjustments to correct for unusual swings in blood sugar that result from known or unknown causes. As you can see, your regimen is not dealing with the blood sugar rise before supper. Talk to your health care team about this pattern you see developing.
Exercise can sometimes result in low blood sugar that night or the next day.
A day of skiing or 18 holes of golf can result in low blood sugar levels during your sleep that night or even the next day. Whenever you exercise strenuously, it's a good idea to check your blood sugar more frequently. Eat extra carbohydrate as needed during the next 24 hours, or adjust your insulin dose. You can control this to some extent by injecting insulin into the abdominal area, because it is absorbed better there. A third factor may be that you forgot your nighttime snack.