The Association Between Sustained HbA1c Control and Long-Term Complications Among Individuals with Type 2 Diabetes: A Retrospective Study

Abstract

Introduction: The prevalence of type 2 diabetes (T2D) represents a rising burden in the US and worldwide, with the condition shown to be associated with relatively large human and economic costs. Part of the reason for such high costs associated with T2D is that the condition is often accompanied by additional health-related complications. The goal of this research is to examine the association between glycemic control and diabetes-related complications for individuals with T2D.

Methods: The Optum Clinformatics® Data Mart (CDM) database from 2007 to 2020 was used to identify adults with T2D. Individuals were classified as having sustained glycemic control (all hemoglobin A1c [HbA1c] < 7%) or poor glycemic control (all HbA1c ≥ 7%) over the 5-year post-period, and diabetes-related complications were identified based upon the Diabetes Complications Severity Index. Multivariable analyses examined the association between sustained glycemic control and diagnosis of a diabetes-related complication in the post-period.

Results: Maintaining HbA1c < 7% over the 5-year post-period, compared to maintaining HbA1c ≥ 7%, was associated with reduced odds of the diabetes-related complications of cardiovascular disease (odds ratio [OR] = 0.76, 95% confidence interval [CI] 0.61-0.94), metabolic disease (OR = 0.37, 95% CI 0.22-0.600), neuropathy (OR = 0.62, 95% CI 0.45-0.84), nephropathy (OR = 0.81, 95% CI 0.69-0.94), and peripheral vascular disease (OR = 0.52, 95% CI 0.33-0.83). There was no statistically significant association between sustained glycemic control and cerebrovascular disease.

Conclusions: Sustained glycemic control was found to be associated with significant reductions in the odds of being diagnosed with diabetes-related complications over a 5-year post-period.

Keywords: Complications; Diabetes complications severity index; Hemoglobin A1c (HbA1c); Odds ratios (OR); Type 2 diabetes (T2D).

Fig. 1

Inclusion/exclusion criteria and sample size. A: Identification window for each patient was dictated by the start and stop of their continuous enrollment period, the requirement of a 1-year pre-period, and the requirement of a 5-year post-period. The first recorded HbA1c result in the identification window was identified as the index date. B: Based upon receipt of ≥ 1 diagnosis of T2D, no receipt of any diagnoses of type 1 diabetes, and filling of at least 1 prescription for a glucose-lowering agent. C: To exclude patients with a source code that recorded a large number of HbA1c results

Fig. 2

Association between sustained glycemic control (HbA1c < 7%) and the likelihood of diabetes-related complications. Results from multivariable logistic regressions which controlled for patient characteristics (age, sex, race, region, insurance type), pre-period general health and comorbidities (adjusted CCI, anxiety, depression, and hypoglycemia), pre-period resource utilization (visits to cardiologist, endocrinologist, nephrologist, nutritionist, ophthalmologist, and number of family practice/internist visits), and pre-period medication use (number of classes of insulin prescribed, number of classes of non-insulin GLAs prescribed, and number of non-GLAs prescribed). Dependent variable is sustained HbA1c < 7% (compared to sustained HbA1c ≥ 7%)

Fig. 3

Sensitivity analyses examining the association between sustained HbA1c ≤ 6.5% and diabetes-related complications. Results from multivariable logistic regressions which controlled for patient characteristics, pre-period general health and comorbidities, pre-period resource, and pre-period medication use. Sample size: 3730

Fig. 4

Sensitivity analyses examining the association between index HbA1c < 7% and diabetes-related complication results from multivariable logistic regressions which controlled for patient characteristics, pre-period general health and comorbidities, pre-period resource, and pre-period medication use. Sample size: 6037