My blood sugar is 4.9-6 mmol/L [88- 108 mg/dl] every morning, and a little higher most evenings after dinner (8-10 mmol/L [144-180 mg/dl]). Is this okay? What is the best level to keep your blood sugar?

It looks like your “fasting” blood sugars (first thing in the morning) are good, but you are too high after meals. Your goals should be less than 120 mg/dl [6.7 mmol/L] before every meal and less than 140 mg/dl [7.8 mmol/L] at exactly two hours after you start eating. Overall, your hemoglobin A1c should be less than 6.5 %. Ask your doctor how you can lower your post meal blood sugars.

JS
Additional comments from Dr. Jim Lane:

Blood glucose levels are usually normalized to plasma glucose levels by the individual meters. That means that the meter measures blood glucose, makes a calculation to make it plasma glucose, and reports the plasma glucose. These should be below 120 mg/dl [6.7 mmol/L] before meals and below 160 mg/dl [8.9 mmol/L] two hours after meals. These results should be verified with quarterly hemoglobin A1c levels to make sure the results are on target overall. Sounds like you are doing reasonably okay.

JTL