Is the production of insulin through genetic engineering?
Yes,most modern drugs like insulin are produced by genetically modified bacteria
Diabetes may not be reversed in all patients with lifestyle changes but it helps to keep it under control and prevent it's complications.
Hyperinsulinemia increases the risk of obesity, type 2 diabetes, and cardiovascular disease and decreases health span and life expectancy. In epidemiological studies, high-dose insulin therapy is associated with an increased risk of cardiovascular disease.
Diabetes mellitus refers to a group of diseases that affect how your body uses blood sugar (glucose) and is diagnosed when fasting blood sugar of 126 mg/dl or more, post prandial blood sugar of 200 or more with glycated hemoglobin of 6.5% or more is seen on tests. Treatment is either tablets or insulin to control blood sugar levels along with life style modifications (Diet + exercise)
Exact cause is unknown but most appreciated hypothesis is either low insulin or insulin resistance due to genetic +/- environmental factors.