The study you are thinking of may be F. Cameron, “The Impact of Diabetes on Brain Function in Children and Adolescents,” Pediatric Clinics of North America, 62 (4) 911-927 (2015), which says, “The most neurotoxic milieu seems to be young age and/or diabetic ketoacidosis at onset, [and] severe hypoglycemia under the age of 6 years followed by chronic hyperglycemia.”
Some people with diabetes seem to deal with it by shouting to the rooftops about how it is no problem at all, while others are constantly gloomy about it. After 51 years as a type 1 diabetic, I would say the experience is about in the middle of those two extremes, and honestly speaking, the disease reduces my quality of life by about 50%. Some type 1 diabetics can live for 60 years and more with the disease with minimal complications, while others, such as one patient I knew, are blind and on dialysis in their early thirties. You do what you can and hope that your genetic disposition to develop the complications is weak.
For your particular situation, I recognize that it is difficult to balance your desire to protect your child from illness against the importance of bringing your child up to be psychologically normal, which means not overburdening her with worry.
The best way to balance those two opposing concerns in my own view would be to forget about diabetes monitoring until the first symptoms appear, since in the current state of medical technology there are only experimental approaches which can delay onset for a short while, and the most effective of these, cyclosporine, is toxic.