Key takeaways:

• Of the study group, 31.7% developed diabetic nephropathy during a mean follow-up of 6 years.
• Adults with type 2 diabetes who slept at least 7 hours per night had higher risk for diabetic nephropathy.

Adults with type 2 diabetes who sleep 7 hours or more per night may have elevated risk for developing diabetic nephropathy, according to data published in the Journal of the Endocrine Society.

“Diabetic kidney disease is a major complication of diabetes and can eventually lead to kidney failure and an increased risk of cardiovascular disease,” Tomoya Mita, MD, PhD, assistant professor of endocrinology, diabetes and metabolism at Juntendo University Graduate School of Medicine in Tokyo, said in a press release. “Sleep is a simple and routinely experienced aspect of daily life, so our findings suggest that longer sleep duration may provide a useful clue to identify people with diabetes who may need closer attention to their kidney health.”

Data were derived from Ikeda F, et al. J Endocr Soc. 2026;doi:10.1210/jendso/bvag201.

Researchers obtained data from 678 adults aged 25 to 69 years with type 2 diabetes who attended outpatient clinics at three institutions in Japan. Diabetic nephropathy was considered a composite of the first occurrence of microalbuminuria or macroalbuminuria, or progression from microalbuminuria at baseline to macroalbuminuria at follow-up. Adults with creatinine of 30 mg/g to 300 mg/g were considered to have microalbuminuria, and those with creatinine of 300 mg/g or higher were defined as having macroalbuminuria. Sleep duration was self-reported and collected at baseline, 2 years and 5 years.

During a mean follow-up of 6 years, 31.7% of study participants developed diabetic nephropathy.

Participants who reported sleeping 7 to less than 8 hours per night (HR = 1.56; 95% CI, 1.05-2.31) or at least 8 hours per night (HR = 1.92; 95% CI, 1.15-3.19) had greater risk for diabetic nephropathy than adults who slept less than 6 hours per night (P for trend = .003).

In a subgroup analysis, sleeping 8 or more hours per night was not linked to increased risk for diabetic nephropathy among adults with normoalbuminuria at baseline. Adults with microalbuminuria at baseline who slept longer had increased risk for diabetic nephropathy. In another subgroup analysis stratified by age, adults aged 65 years and older had increased risk for diabetic nephropathy if they slept longer. No association was seen among adults younger than 65 years (P for interaction = .046).

The researchers noted that the demographics of the participants in the study differed from other previously published research.

“In previous studies, people with longer sleep duration generally had higher BMI and adverse metabolic profiles, supporting a metabolically driven pathway,” the researchers wrote. “In contrast, in our study, participants with longer sleep duration had lower BMI and lower LDL cholesterol levels, with HbA1c levels being lowest in the 7 to less than 8 hours group. This difference suggests that, particularly among older participants, longer sleep duration may reflect underlying physiological vulnerability rather than metabolic excess.”

In the press release, Mita noted that the study was observational and does not establish causality between sleep duration and diabetic nephropathy.

“Importantly, our findings do not show that long sleep directly causes kidney disease; rather, longer sleep may be a readily observable marker of underlying health vulnerability,” Mita said in the press release.