The following is a table showing the risks of retinopathy based on an individual’s HbA1c level over a number of years. This data is reproduced with the kind permission of Ron Sebol who collated the data. This data was also used in Gretchen Becker’s book “Type 2 Diabetes – The First Year”
So for example, an individual with an HbA1c of 9% will have a 2.58% risk of retinopathy after 2 years. After 15 years, there is an 88.69% chance of retinopathy
So this data demonstrates the importance of glycemic control for diabetics. By reducing the A1c we can see the reduction in risks of complications. Over a period of 15 years a diabetic with an HbA1c of 7% has 4 times more risk of developing retinopathy than a diabetic with an HbA1c of 6%. If the HbA1c is 8% over that time period, then the risks are 16 times greater. As can be seen from the table, higher HbA1c levels guarantee retinopathy after a number of years.
For further information regarding Hba1c I append this table which shows a correlation between the Hba1c and the blood glucose levels you will be running to achieve that Hba1c