Effects of a Mediterranean diet on the development of diabetic complications: A longitudinal study from the nationwide diabetes report of the National Program for Prevention and Control of Diabetes (NPPCD 2016-2020)

Abstract

Objective: To evaluate the effectiveness of a Mediterranean dietary pattern on the incidence of macrovascular and microvascular complications of diabetes, namely cardiovascular disease (CVD), diabetic foot disorders, diabetic retinopathy, nephropathy, and neuropathy.

Methods: This longitudinal study was conducted among 71392 adults with diabetes who attended academic tertiary-care outpatient clinics from February 2016 to March 2020 across Iran using the National Program for Prevention and Control of Diabetes database. Among them, 22187 patients with diabetes (type 1 and type 2) completed 2-11 follow-up visits after baseline registration. The association between adherence to a Mediterranean diet and diabetic complications was assessed using pooled logistic regression models. This association was adjusted for potential confounders. The effect of time was assessed using fractional polynomials.

Results: A total of 22187 participants were included in the analysis (30.22% men and 69.78% women) with either type 1 (mean age 50.7 years) or type 2 (mean age 59.9 years) diabetes. After adjustment for confounding variables, there was a negative correlation between adherence to a Mediterranean diet and the incidence of CVD among patients with type 1 diabetes (T1D) and 2 diabetes (T2D) (OR= 0.53, 95% CI: 0.37 - 0.75, p-value <0.001 and OR= 0.61, 95% CI: 0.57 - 0.89, p-value <0.001, respectively). Also, the diet had a statistically significant protective effect against incident symptomatic neuropathy (OR= 0.32, 95% CI: 0.23 - 0.43, p-value <0.001, and OR= 0.68, 95% CI: 0.64 - 0.72, p-value <0.001, respectively), nephropathy (OR= 0.42, 95% CI: 0.30 - 0.58, p-value <0.001, and OR= 0.88, 95% CI: 0.80 - 0.96, p-value= 0.007, respectively), and retinopathy (OR= 0.32, 95% CI: 0.24 - 0.44, p-value <0.001, and OR= 0.68, 95% CI: 0.61 - 0.71, p-value <0.001, respectively) in T1D and T2D.

Conclusion: The Mediterranean dietary pattern is associated with a lower incidence of CVD and microvascular complications (i.e. diabetic retinopathy, nephropathy, and neuropathy) among a cohort of patients with T1D and T2D in Iran.

Keywords: Cardiovascular diseases; Diabetes; Diabetic complications; Mediterranean diet; Nephropathy; Neuropathy; Retinopathy.