Table 1.

Summary of results from RCTs and follow-up studies

Study	Study duration (years)	No. of participants	Mean HbA1c at end of trial	Study findings	Follow-up study period post-trial (years)	Significant legacy effect finding
DCCT	6.5	1441 with recently diagnosed T1D	Intensive: 7.4% (57 mmol/mol) Control: 9.1% (76 mmol/mol)	Decreased rates of microvascular disease in intensive arm No difference in macrovascular disease	17–30	Decreased rates of microvascular disease and macrovascular disease in intensive control arm at follow-up
UKPDS	5	4209 with newly diagnosed T2D	Intensive: 7.0% (53 mmol/mol) Control: 7.9% (63 mmol/mol)	Decreased risk of microvascular disease in intensive arm Non-significant reduction in macrovascular disease	10	Decreased rates of microvascular disease, reduction in MI and mortality in intensive control arm at follow-up
Steno-2	7.8	160 with T2D and microalbuminuria	Intensive: 7.9% (63 mmol/mol) Control: 9.0% (75 mmol/mol)	Decreased rates of microvascular disease in intensive arm	5.5	Decreased rates of microvascular disease, lower rates of CV events, CV mortality and all-cause mortality in intensive control arm at follow-up
ADVANCE and ADVANCE-ON	5	11,140 with pre-existing diabetes (mean duration 8 years)	Intensive: 6.5% (48 mmol/mol) Control: 7.3% (56 mmol/mol)	Decreased rates of microvascular disease in intensive arm No significant difference in macrovascular disease	5.4	Lower rates of ESRD in intensive control arm at follow-up
ACCORD and ACCORDION	3.5	10,251 with pre-existing diabetes (mean duration 10 years)	Intensive: 6.4% (46 mmol/mol) Control: 7.5% (78 mmol/mol)	Increased mortality in intensive control arm Decreased rates of non-fatal CV events	4	No effect on primary outcome of CV events Decreased rates of retinopathy in intensive control group
VADT	5.6	1791 with pre-existing diabetes (mean duration 11.5 years)	Intensive: 6.9% (52 mmol/mol) Control: 8.4% (68 mmol/mol)	No significant difference in macrovascular events between arms	10–15	Reduction in macrovascular events in intensive control arm at 10 years follow-up but effect was lost at 15 years
ADN CKD 3–4	2	120 with pre-existing diabetes and advanced nephropathy (mean duration 15 years)	Intensive: 7.3% (56 mmol/mol) Control: 8.3% (67 mmol/mol)	Decreased rate of progression to ESRD in intensive arm	2	No significant difference in progression to ESRD between arms at follow-up

Study duration is presented as mean, except for ADVANCE (median), ACCORD (study stopped at 3.5 years due to increased mortality in intensive control group) and ADN CKD 3–4 (median 2 years) ADVANCE-ON, ADVANCE Observational Study; CV, cardiovascular; MI, myocardial infarction; T1D, type 1 diabetes; T2D, type 2