Progression of diabetic retinopathy is associated with increased HbA1c, whereas risk factors for diabetic nephropathy include HbA1c variability and dyslipidemia, according to findings published in the Journal of Diabetes Investigation.
“It is well-established that long-term exposure to hyperglycemia is the major risk factor for both [diabetic retinopathy] and [diabetic nephropathy]. Each complication has a strong impact on the initiation or progression of the other,” KiHo Song, MD, PhD, of the division of endocrinology and metabolism in the department of internal medicine at The Catholic University of Korea in Seoul, and colleagues wrote. “However, the progression of [diabetic retinopathy] and [diabetic nephropathy] can be discordant in diabetic patients.”
Using data from electronic medical records from Yeouido St. Mary’s Hospital in Seoul, South Korea, Song and colleagues conducted a 3-year retrospective cohort study of adults with type 2 diabetes who visited the hospital from July 2013 to December 2013 (n = 604). HbA1c was measured every 3 to 6 months and progression of diabetic nephropathy was determined by an estimated glomerular filtration rate decline of more than 12%.
Progression of diabetic nephropathy was seen in 34 participants (mean age, 64.7 years; 35.3% women). Older age (P = .006), greater insulin use (P < .0001) and frequent smoking (P = .004) were all characteristics of those who had diabetic nephropathy progression. The researchers also found that progression of diabetic nephropathy was significantly predicted by HbA1c variability (OR = 3.02; 95% CI, 1.28-7.1) and the higher ratio of triglyceride to HDL cholesterol (OR = 1.15; 95% CI, 1.02-1.29).
“The deleterious effect of low HDL cholesterol level on the progression of [diabetic nephropathy] could be explained by the fact that HDL plays a protective role in renal damage by reducing oxidative stress and inflammation,” the researchers wrote.
Progression of diabetic retinopathy was reported in 68 participants in the study. Characteristics of the group included longer diabetes duration (P = .019), higher BMI (P = .017), hypertension (P = .024) and greater insulin use (P = .019) compared with those who did not show progression. Mean HbA1c levels were also higher in those with diabetic retinopathy progression compared with those without (P = .001), with mean HbA1c measurements (OR = 1.35; 95% CI, 1.02-1.78) the only significant predictor of progression.
“Long-term glycemic control, expressed as the HbA1c level, is crucial for preventing the initiation and progression of both [diabetic retinopathy] and [diabetic nephropathy],” the researchers wrote. “Although the reason of the harmful effects of HbA1c variability on the development of [diabetic retinopathy] or [diabetic nephropathy] are not clear, one possible mechanism involves ‘metabolic memory’ from repeated exposure to glycemic instability, which can lead to increased oxidative stress.” – by Phil Neuffer
Disclosures: The authors report no relevant financial disclosures.