Eye Focusing Ability Can Predict Glycated Hemoglobin Level of Type-1 Diabetes Patients

Glycated Hemoglobin (HbA1c) is crucial for diagnosing and monitoring diabetes. However, current tests are complex, invasive, costly, and often met with low compliance. This study aimed to find whether simple clinical, noninvasive measures of the ocular accommodation function may predict the glycated hemoglobin results in type-1 diabetes mellitus.

In a single-examiner-blind study, Near Point of Accommodation (NPA) and Lag of Accommodation (LoA) were compared between type-1 diabetes patients and controls. NPA was measured by the push-up-to-blur method, LoA by the Monocular Estimation Method (MEM) retinoscopy, and glycated hemoglobin was recorded with a Point-of-Care (POC) HbA1c analyzer. The independent t-test was employed to assess the difference in means between groups. Correlational analysis was conducted to examine the relationship between HbA1c levels and accommodative measures. Additionally, Structural Equation Modeling (SEM) was utilized to evaluate the interrelationships among variables and to determine the extent to which the model could explain the variance in HbA1c.

Diabetic patients had a receded mean NPA (15.16 ± 4.53 cm) compared to controls (9.48 ± 1.43 cm; p < 0.001). When converted to the Amplitude of Accommodation (AoA) in diopters (D), the mean AoA was lower in diabetics (6.6 ± 2.28D) than in controls (10.55 ± 1.52D; p < 0.001). Diabetics had a higher mean LoA (0.983 ± 0.74D) than controls (0.156 ± 0.44D; p < 0.001). After controlling for age (β = -0.167, p = 0.017) and the duration of diabetes mellitus (DM) (β = 0.665, p = 0.051), the SEM analysis indicated that the NPA was a significant predictor of HbA1c levels, with a path coefficient estimate (β) of 0.345 (p < 0.001). In contrast, the LoA did not significantly predict HbA1c levels (β = 0.005, p = 0.993). The model explained 38.7% of the variance in HbA1c, indicating a satisfactory fit to the experimental data.

The study found eye accommodation was significantly affected in recent type-1 diabetes patients, indicating its sensitivity to diabetes. SEM using these ocular measures accounts for one-third of HbA1c variance. Thus, accommodative function assessments could be a simple, noninvasive, and cost-effective method for evaluating HbA1c levels. LoA is not a good predictor of HbA1c.