Time in Target Range for Hemoglobin A_1c and Systolic Blood Pressure: Association With Adverse Kidney Events

Time in target range (TTR) for systolic blood pressure (SBP) and hemoglobin A_1c (HbA_1c) integrates information about average and variability of levels over time. Their impact on kidney outcomes has not been fully evaluated. This study investigated the association of HbA_1c-TTR and SBP-TTR, individually and jointly, with kidney outcomes among patients with type 2 diabetes and hypertension.

Post hoc observational cohort analysis of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial data.

6,542 ACCORD participants with ≥ 3 HbA_1c and SBP measurements during the first 12 months.

HbA_1c-TTR and SBP-TTR during the first 12 months after randomization, each categorized separately as either 100% or in tertiles among the remaining study participants. In addition, 4 categories jointly assessing TTR for HbA_1c and SBP were created: both HbA_1c-TTR and SBP-TTR ≤ 80%, HbA_1c-TTR ≤ 80% and SBP-TTR > 80%, HbA_1c-TTR > 80% and SBP-TTR ≤ 80%, and both HbA_1c-TTR and SBP-TTR > 80%.

A composite kidney outcome, defined as incident albuminuria, estimated glomerular filtration rate decline ≥ 40% from baseline, or kidney failure.

Associations of HbA_1c-TTR and SBP-TTR, individually and in combination with kidney outcomes, were analyzed using Cox proportional hazards models.

Compared with HbA_1c-TTR of ≤ 49.6% (the lowest tertile), HbA_1c-TTR of 100% was associated with a 20% lower risk of the composite kidney outcome (HR, 0.80 [95% CI, 0.68-0.94]). Compared with SBP-TTR of ≤50.7% (the lowest tertile), SBP-TTR of 100% was associated with a 32% lower risk of the composite kidney outcome (HR, 0.68 [95% CI, 0.58-0.80]). Participants with both HbA_1c-TTR and SBP-TTR > 80% had a 29% (HR, 0.71 [95% CI, 0.61-0.83]) lower risk of the composite kidney outcome compared with participants with both HbA_1c-TTR and SBP-TTR ≤ 80%.

Limited duration of follow-up and low number of kidney failure events.

Longer time with HbA_1c and SBP within target range was associated with a lower risk of adverse kidney events.

The concept of "time in target range" (TTR), defined as the proportion of time within a defined range, has been proposed in managing diabetes and hypertension. The combined effect of hemoglobin A_1c (HbA_1c)-TTR and systolic blood pressure (SBP)-TTR on adverse kidney events remains unknown. We evaluated the association of HbA_1c-TTR and SBP-TTR, both individually and in combination, with incident kidney outcomes among patients who were enrolled in a clinical trial. We found that higher HbA_1c-TTR and SBP-TTR were individually associated with a lower risk of adverse kidney events in patients with type 2 diabetes and hypertension. Having more time with both HbA_1c and SBP within target range was also associated with a lower risk of adverse kidney outcomes compared with having either 1 individual parameter or neither individual parameter within target range.