A socioeconomic and behavioral survey of patients with difficult-to-control type 2 diabetes mellitus reveals an association between diabetic retinopathy and educational attainment

Abstract

Background: We have recently reported that the attitude of patients toward risk could be a factor in the progression of diabetic complications. In general, risk preference is closely related to socioeconomic status (SES), which includes factors such as age, sex, income, and educational attainment.

Objective: We aimed to determine the effect of SES and behavioral propensity on the progress of diabetic complications in patients with type 2 diabetes mellitus (T2DM).

Methods: We conducted a survey of 238 patients with difficult-to-control T2DM treated at a hospital in Japan using a modified behavioral economics questionnaire that included questions related to SES. The patients had been referred by general practitioners or other departments in the hospital because of poor metabolic control or unstable complications.

Results: Educational attainment was significantly associated with progression of retinopathy in patients <65 years of age. Educational attainment of a high school diploma (12 years of education) or lower was a significant risk factor, but there were no differences among levels of attainment beyond high school (13-16 years or more of education). Behavioral propensities were also weakly associated with complications, but not as much as educational attainment. Personal income level and economic status did not show an association with the retinopathy levels.

Conclusion: Lower educational attainment is a strong risk factor for diabetic retinopathy, and it is independent of the economic status. The result suggests that cognitive function may play an important role in the progression of diabetic retinopathy in patients with T2DM.

Keywords: behavioral economics; cognitive function; diabetic nephropathy; economic status; income.

Figure 1

Association between retinopathy level and educational level attainment in participants with T2DM. Notes: (A) <65 years of age; (B) ≥65 years of age, educational attainment (total educational years): junior high school (9 years); high school (12 years); vocational college (13–15 years); junior college including technical college (14–15 years); university including graduate school (≥16 years). Retinopathy levels; NDR, SDR, PPDR, PDR, and PRP. Pearson’s χ² test: <65 years of age: n=126, χ² 21.58, P=0.0058; ≥65 years of age: n=104, χ² 3.58, P=0.89. Abbreviations: NDR, no diabetic retinopathy; PPDR, preproliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy; PRP, panretinal photocoagulation; SDR, simple diabetic retinopathy; T2DM, type 2 diabetes mellitus.

Figure 2

Comparison of (A) personal and (B) household income by retinopathy level for participants with T2DM <65 years of age. Notes: Retinopathy levels: NDR, SDR, PPDR, PDR, and PRP. Kruskal–Wallis rank sum test: personal income: χ² 1.33, P=0.51; household income: χ² 6.87, P=0.032. Abbreviations: JPY, Japanese Yen (JPY 1 million = USD 10,000); NDR, no diabetic retinopathy; PDR, proliferative diabetic retinopathy; PPDR, preproliferative diabetic retinopathy; PRP, panretinal photocoagulation; SDR, simple diabetic retinopathy; T2DM, type 2 diabetes mellitus.

Figure 3

Comparison of (A) personal and (B) household income by educational attainment for participants with T2DM <65 years of age. Notes: Educational attainment (total educational years): junior high school (9 years); high school (12 years); vocational college (13–15 years); Junior college including technical college (14–15 years); university including graduate school (≥16 years), Kruskal–Wallis rank sum test: personal income: χ² 14.01, P=0.0073; household income: χ² 10.87, P=0.028. Abbreviations: JPY, Japanese Yen (JPY 1 million = USD 10,000); T2DM, type 2 diabetes mellitus.