The Threshold of the Severity of Diabetic Retinopathy below Which Intensive Glycemic Control Is Beneficial in Diabetic Patients: Estimation Using Data from Large Randomized Clinical Trials

Table 1

Characteristics of included studies.

Study	Author and year	Country	Age (years) (IG vs. CG)	DM type	Follow-up (years)	HbA1c at baseline (IG vs. CG)	Achieved HbA1c (IG vs. CG)
DCCT	DCCT group, 1993	USA	27	T1DM	10	Primary prevention: 8.8%; secondary prevention: 8.9%	7.2% vs. 8.0%
UKPDS	UKPDS group, 1998	UK	63	T2DM	15	9.3% vs. 9.4%	7.1% vs. 7.9%
VADT	Duckworth 2009, Azad 2014	USA	60	T2DM	6	9.3% vs. 9.4%	6.9% vs. 8.4%
ACCORD	ACCORD group, 2010	USA	61.6	T2DM	4	8.2% vs. 8.2%	7.1% vs. 9.4%
AdRem	Beulens, 2009	20 countries	66	T2DM	4.1	7.4% vs. 7.4%	6.49% vs. 7.24%

DM = diabetes; T1DM = type 1 diabetes; T2DM = type 2 diabetes; IG = intensive glycemia control group; CG = conventional glycemic control group.