Type 2 diabetes: an analysis explores an HbA1c target below 6.5%, without establishing an optimal threshold

A new analysis of J-DOIT3 data

The J-DOIT3 trial enrolled 2,542 participants, split between conventional and intensive treatment, with 1,271 people initially assigned to each group. Two ineligible participants were subsequently excluded from the analyses.

During a median follow-up of 8.5 years, severe hypoglycemia was rare: seven events in the intensive group and four in the conventional group. In this context, the researchers reexamined the levels of several risk factors associated with cardiovascular events and mortality.

The analysis uses a landmark one year after the start of the trial. It then uses updated mean levels of HbA1c, systolic blood pressure, and LDL and HDL cholesterol.

A suggested target, not a demonstrated optimum

For HbA1c, the researchers found no clearly identifiable lower threshold associated with the lowest risk of myocardial infarction or all-cause death. Nevertheless, they suggest that a target below 6.5% could be relevant to mortality in this population, in which severe hypoglycemia was uncommon.

These two findings must be considered together: the 6.5% threshold is a possible interpretation, not an established optimum. The abstract provides neither the magnitude of the association with mortality, nor its uncertainty intervals, nor the corresponding absolute risks. It therefore does not allow any potential benefit to be quantified.

What this analysis cannot determine

Although the data come from a randomized trial, this analysis links observed biological levels to subsequent events. It does not directly compare an HbA1c target below 6.5% with another target through random assignment. It therefore does not demonstrate that lowering HbA1c causes a reduction in mortality.

The rarity of severe hypoglycemia also limits the scope of the finding: this conclusion does not automatically apply to people who experience it frequently. This analysis alone does not justify changing your blood glucose target or treatment without discussing it with the healthcare professional managing your diabetes.

What we can take away

The finding opens up an avenue for exploring blood glucose targets when severe hypoglycemia is rare. It establishes neither a universal target below 6.5% nor a demonstrated survival benefit.