Longitudinal trends in HbA_1c patterns and association with outcomes: A systematic review

Abstract

BackgroundThis study aimed to review studies that identified patterns of longitudinal HbA1c trends in patients with diabetes and to summarize factors and outcomes associated with distinct trajectory patterns.MethodsPubMed and Web of Science were systematically searched for studies examining HbA1c trends among patients with diabetes from database inception through September 2017. Articles were included if they met the following inclusion criteria: (a) longitudinal study of subjects with diabetes only, (b) use of serial measurements of HbA1c, and (c) analysis of the trend of HbA1c using group‐based trajectory approaches.ResultsTwenty studies were included, 11 on type 1 diabetes and 9 on type 2 diabetes. These studies identified 2 to 6 HbA1c trajectory patterns. The most commonly identified patterns included stable HbA1c around 7.0% and at levels between 8.0% and 9.9%, which usually captured the HbA1c pattern among the majority of subjects in the study population. Unstable patterns identified included increasing HbA1c trend, decreasing HbA1c trend, and non‐linear patterns. These patterns were associated with differential risk of disease outcomes, over and beyond single‐point HbA1c measures. Age, gender, ethnicity, diabetes duration, disease management frequency, cardiovascular risk factors, insulin treatment, family environment, and psychosocial factors were the most frequently reported factors associated with membership of specific HbA1c pattern groups.ConclusionCommon patterns of longitudinal HbA1c trends were identified despite heterogeneity among the studies. A better understanding of what underlies these different patterns may provide opportunities to tailor therapies and care for these patients to reduce adverse outcomes.

Five heterogeneous HbA1c trajectories from childhood to adulthood in youth with type 1 diabetes from three different continents: A group‐based modeling approach

“…Prior studies of type 1 diabetes using GBT modeling have allowed researchers to identify stable, increasing, and even decreasing trajectories of HbA1c among youth. A recent systematic review demonstrated that the majority of youth follow a stable trajectory, while a smaller percentage of subjects follow a trajectory that changes over time . The authors of that review highlighted the need to better understand factors that contribute to longitudinal HbA1c trends; our results emphasize the heterogeneity of factors that predict changes in HbA1c over time across different populations.…”

“…The difference in findings may be explained by the more limited scope of that study, which included only 239 youth (9‐11 years old) transitioning to adolescence; youths were observed for only 36 months. Similar to our study, other authors have reported that minority status is associated with higher or deteriorating glycemic control over time . It seems likely that socioeconomic status, family structure and dynamics, and engagement with self‐management might mediate at least some of that association.…”

Distinct trajectories of HbA1c in newly diagnosed Type 2 diabetes from the DPV registry using a longitudinal group‐based modelling approach

“…A recent systematic review included nine studies based on heterogeneous populations . In line with the present study, the largest group identified in that review showed stable good glycaemic control over time, containing 44% to 83% of participants . The second largest groups were those with stable moderately high levels (13% to 38%) .…”

“…In line with the present study, the largest group identified in that review showed stable good glycaemic control over time, containing 44% to 83% of participants . The second largest groups were those with stable moderately high levels (13% to 38%) . There were small groups of individuals who maintained high HbA 1c levels over time (3% to 15%) .…”

Longitudinal trends in HbA1c in diabetes: Stable means can hide meaningful long‐term changes

“…We were interested by the recent article from Miyang Luo et al, 1 who reviewed longitudinal studies of subjects with both types of diabetes and described long-term trends in HbA1c. For type 1 diabetes, they identified stable, low to moderate (7.1% to 9% HbA1c) as the main pattern, whereas extremely low or high but stable, deteriorating or improving HbA1c were possible for a minority of subjects: 2% to 45% among the 11 reviewed studies.…”