Disparities in Hemoglobin A1c Testing During the Transition to Adulthood and Association With Diabetes Outcomes in Youth-Onset Type 1 and Type 2 Diabetes: The SEARCH for Diabetes in Youth Study

OBJECTIVE To identify correlates of hemoglobin A(1c) (HbA(1c)) testing frequency and associations with HbA(1c) levels and microvascular complications in youth-onset diabetes. RESEARCH DESIGN AND METHODS The SEARCH for Diabetes in Youth study collected data from individuals diagnosed with diabetes before age 20 at 8 years (n = 1,885 type 1, n = 230 type 2) and 13 years (n = 649 type 1, n = 84 type 2) diabetes duration. We identified correlates of reporting >= 3 HbA(1c) tests/year using logistic regression. We examined associations of HbA(1c) testing with HbA(1c) levels and microvascular complications (retinopathy, neuropathy, or nephropathy) using sequentially adjusted linear and logistic regression. RESULTS For type 1 diabetes, odds of reporting >= 3 HbA(1c) tests/year at 8 and 13 years diabetes duration decreased with older age at diagnosis (odds ratio [OR] 0.91 [95% CI 0.88-0.95]), longer duration of diabetes (OR 0.90 [0.82-0.99]), not having a personal doctor (OR 0.44 [0.30-0.65]), and lapses in health insurance (OR 0.51 [0.27-0.96]). HbA(1c) testing >= 3 times/year over time was associated with lower HbA(1c) levels (OR -0.36% [-0.65 to -0.06]) and lower odds of microvascular complications (OR 0.64 [0.43-0.97]) at 13 years' duration, but associations were attenuated after adjustment for HbA(1c) testing correlates (OR -0.17 [-0.46 to 0.13] and 0.70 [0.46-1.07], respectively). For type 2 diabetes, not seeing an endocrinologist decreased the odds of reporting >= 3 HbA(1c) tests/year over time (OR 0.19 [0.06-0.63]), but HbA(1c) testing frequency was not associated with HbA(1c) levels or microvascular complications. CONCLUSIONS We observed disparities in HbA(1c) testing frequency predominately by health care-related factors, which were associated with diabetes outcomes in type 1 diabetes.

Automated summary

Disparities in HbA(1c) testing frequency were observed primarily based on health care-related factors, which were associated with diabetes outcomes in type 1 diabetes. Higher frequency of HbA(1c) testing was linked to lower HbA(1c) levels and decreased odds of microvascular complications over time. However, these associations were attenuated after adjusting for HbA(1c) testing correlates.