When should we measure blood sugar?

For normal individuals, at least once in a year as a part of annual health checkups.
Immediately if there are following signs such as-
Fatigue and tiredness
Frequent infections (Urinary tract infections & balanoposthitis)
Increased hunger, thirst and urination
Frequent nocturia
Dental issues
Blurred Vision
Numbness of hands or feet
Non-healing or slow healing wounds
Since, type 2 diabetes has been rampant in the last 10-20 years even in pediatric and young adults; it is wise to measure blood glucose once in a year even in this population.
For diabetics, frequent monitoring (weekly) until the blood sugars are under control and once in every 2 weeks or monthly thereafter.