Previously, CGMs required frequent calibration with fingerstick glucose testing. Also their results were not accurate enough so that people always had to do a fingerstick to verify a reading on their CGM before calculating a dose of insulin (for example before meals or to correct a high blood sugar). However, recent technological advances have improved CGMs. One professional CGM can be worn for up to 14 days without calibration. Another personal CGM can be used to guide insulin dosing without confirmation by fingerstick glucose. Finally, there are now systems in which the CGM device communicates with insulin pumps to either stop delivery of insulin when blood glucose is dropping (threshold suspend), or to give daily insulin (hybrid closed loop system).
2.Retinopathy - Diabetes may cause blood vessels in the retina (the light sensitive lining of the eye) to become leaky, blocked, or grow abnormally [Figure 1]. Retinopathy is rare before the age of 10 and the risk increases with the length of time a person has diabetes. Treatments such as laser, injections in the eye, or other procedures may be helpful to prevent visual loss or restore sight. The longer a patient has diabetes, the greater chance of developing an eye problem.  All patients with diabetes are at risk for developing retinopathy, but the risk is higher for patients with worse blood sugar control.  Early retinopathy may have no symptoms, but early treatment is essential to prevent any loss of vision.
Sequelae. The long-term consequences of diabetes mellitus can involve both large and small blood vessels throughout the body. That in large vessels is usually seen in the coronary arteries, cerebral arteries, and arteries of the lower extremities and can eventually lead to myocardial infarction, stroke, or gangrene of the feet and legs. atherosclerosis is far more likely to occur in persons of any age who have diabetes than it is in other people. This predisposition is not clearly understood. Some believe that diabetics inherit the tendency to develop severe atherosclerosis as well as an aberration in glucose metabolism, and that the two are not necessarily related. There is strong evidence to substantiate the claim that optimal control will mitigate the effects of diabetes on the microvasculature, particularly in the young and middle-aged who are at greatest risk for developing complications involving the arterioles. Pathologic changes in the small blood vessels serving the kidney lead to nephrosclerosis, pyelonephritis, and other disorders that eventually result in renal failure. Many of the deaths of persons with type 1 diabetes are caused by renal failure.
People with full-blown type 2 diabetes are not able to use the hormone insulin properly, and have what’s called insulin resistance. Insulin is necessary for glucose, or sugar, to get from your blood into your cells to be used for energy. When there is not enough insulin — or when the hormone doesn’t function as it should — glucose accumulates in the blood instead of being used by the cells. This sugar accumulation may lead to the aforementioned complications.