Comparison of glucose time in range and area under curve in range in relation to risk of diabetic retinopathy in type 2 diabetes patients

Abstract

Aims/introduction We proposed a novel continuous glucose monitoring (CGM)‐based metric, area under the curve in range (AucIR), for integrating both the amplitude and duration of dysglycemia, and further compared AucIR with the emerging key CGM‐derived metric, time in range (TIR). Materials and methods A total of 2,030 adult patients with type 2 diabetes were enrolled during May 2020 to October 2021. AucIR and TIR were measured with 7‐day CGM data. Logistic regression analysis and the C ‐statistic was carried out to assess the association of AucIR and TIR with diabetic retinopathy (DR). Results Both AucIR ( r = −0.89) and TIR ( r = −0.95) were strongly correlated with mean glucose levels. Compared with TIR, AucIR showed a tighter relationship with parameters of glycemic variability, including the coefficient of variation ( r = −0.56), standard deviation ( r = −0.89) and mean amplitude of glycemic excursions ( r = −0.70). For each absolute 10% decrease in AucIR, the risk of DR was increased by 7% (95% confidence interval 1.02–1.13) after adjustment for confounders. With respect to TIR, each absolute 10% decrease was associated with an 8% (95% confidence interval 1.03–1.14) increased risk of DR. The model discrimination for DR, as measured by C ‐statistic, did not differ significantly between the two metrics ( P > 0.05). Conclusions AucIR did not provide added benefit over TIR in the assessment of DR risk among patients with type 2 diabetes. The potential value of AucIR needs to be explored in future studies.

Research progress in the application of time in range: more than a percentage

“…[ 10 ] A cross-sectional study comprising 3262 patients with type 2 diabetes found that TIR was significantly linked to all stages of diabetic retinopathy after adjusting for covariates including HbA1c. [ 21 ] Mayeda et al previously demonstrated that less TIR was correlated with a higher risk of diabetic peripheral neuropathy (DPN) assessed using the Michigan Neuropathy Screening Instrument questionnaire in patients with type 2 diabetes and concomitant chronic kidney disease. [ 22 ] In contrast, there was no significant association between HbA1c and DPN symptoms in their study population.…”

“…For instance, the area under the curve in range (AucIR), which integrates both the amplitude and duration of dysglycemia, has been compared with TIR. [ 47 ] Although AucIR was significantly associated with DR, it did not provide more benefits over TIR. Other metrics such as the Glycemia Risk Index (GRI) [ 48 ] and the comprehensive glucose pentagon [ 49 ] have been put forward.…”

“…To provide additional information on glycemia, several novel CGM-derived metrics have been proposed. For instance, the area under the curve in range (AucIR), which integrates both the amplitude and duration of dysglycemia, has been compared with TIR [47] . Although AucIR was significantly associated with DR, it did not provide more benefits over TIR.…”

“…In a post-hoc analysis of the DCCT trial, Beck et al reported that TIR computed from 7-point SMBG data was significantly associated with the development of DR progression and the development of microalbuminuria, suggesting that TIR may be a new marker of microvascular complications in T1DM [10] . A cross-sectional study comprising 3262 patients with type 2 diabetes found that TIR was significantly linked to all stages of diabetic retinopathy after adjusting for covariates including HbA1c [21] . Mayeda et al previously demonstrated that less TIR was correlated with a higher risk of diabetic peripheral neuropathy (DPN) assessed using the Michigan Neuropathy Screening Instrument questionnaire in patients with type 2 diabetes and concomitant chronic kidney disease [22] .…”

Recent updates in factors associated with incidence and screening of diabetic eye disease

“…However, since the influence of glycemia depends on both the duration and the glucose levels, indices that reflect both variables are expected to predict retinopathy better than the conventional glycemic indices. A recent attempt using the ‘area under the curve in range’ was unable to demonstrate a significant association with retinopathy 5 . Nevertheless, further research of similar indices for detailed glycemic status using the new technology is expected.…”