Long-Term Changes in HbA1c According to Blood Glucose Control Status During the First 3 Months After Visiting a Tertiary University Hospital

Background: We evaluated patients visiting a tertiary university hospital due to a diagnosis of diabetes with a goal of achieving blood glucose control and evaluated blood glucose persistence over 7 years according to the change in blood glucose evident at 3 months after the first visit. Methods: Patients treated from 2009 to 2013 were categorized into four groups according to the change in HbA1c levels during the first 3 months of follow-up (Best_group, ≥ 1.6% decrease; Better_group, 0.5–1.5% decrease; Neutral_group, maintained at −0.4% to +0.4%; Worse_group, ≥ 0.5% increase). Each patient’s blood glucose control status was then monitored for 7 years. The incidence of stroke and acute coronary syndrome during this period was confirmed. Results: Overall, 9,776 patients were included. HbA1c values were lower in the Best_group than in the other groups at all time points (all P < 0.001). The rate of reaching targets of < 6.5% or < 7.0% HbA1c decreased over time; the rate at which the estimated glomerular filtration rate decreased to < 30 or < 60 mL/min/1.73m2 increased over time (all trends, P < 0.01). Conclusion: Blood glucose control status in the first 3 months after initiating hospital care enabled estimation of the patient’s glycemic control status for the next 7 years. In cases with poor initial blood glucose control, a new or more active method of blood glucose control should be sought.