Diabetes - or diabetes mellitus as it is known scientifically - is when you have too much sugar (glucose) in your blood. It affects millions of people, and there are several different types.
This introductory article uses American jargon for example 70-180 mg/dL. in uk measurements is 3.9-10.0 mmol/L . So will not be easily understood by novice english readers. It should be understood that going over 10 mmol/l at anytime is likly to cause diabetic complications in the long term and testing should be random periods through the day or use a freetrial of a constant blood sugar monitor such as Libre2. This will show you as a series of graphs how you body is reacting to your food, exercise and drugs minute by minute for weeks enabling you to see what works or not for you.
Emerging (common knowledge) research mainly by Jessie Inchauspé, a biochemist also known as the Glucose Goddess shows the importance of eating complex carbs (small salad) first and simple carbs not at all or at the end of a meal in controlling damaging blood sugar spikes. This research is based on thousands of trials using the Libre2 device. A TV series of research is available to download on Channel 4 called Eat Smart: Secrets of the Glucose Goddess. This approach does not seem to be adopted by the NHS yet but it is effective and safe and should be explored.
The desciption of what happens on a diabetic check is also not consistant with UK practises. We could test for insulin levels as well as blood sugar levels and use this to aid selection of drugs to be used we do not. The insulin level test is only available to people that are getting a insulin injection treatment plan. So drug selection is always trial and error pilling one atop of another until something works. This leads to situations such as ,you produce enough insulin but are given both Metformin and Glicazide (a drug that flogs the pancreass into producing more insulin that damages the organ leading to failure) when the problem was mainly insulin resistance or low incretin hormones that needs a different treatment regime.
British diabetic treatment seems to be based not on diagnosing the cause but on treating the symptoms.