Heterogeneous impacts of carbohydrate subtypes on the progression of microvascular complications in hyperglycemic individuals: evidence from the UK biobank

Abstract

Background: Hyperglycemic individuals, who are prone to microvascular complications of diabetes (MCDs) like diabetic patients, may benefit from timely carbohydrate intake intervention. But there remain inconsistent results and lack of focus on carbohydrate subtypes, which may have distinct effects. This study aimed to investigate the associations between dietary carbohydrate subtypes and the MCDs incidence in hyperglycemic individuals. Methods: Participants with hyperglycemia (defined as having either fasting plasma glucose ≥ 5.56 mmol/L or diabetes mellitus) were included from the UK Biobank cohort. Multivariable-adjusted Cox proportional hazards models and multi-state modelling were employed to estimate the associations of total carbohydrate, free sugars, starch, and fiber intake with incident MCDs (diabetic kidney disease, retinopathy, neuropathy) and all-cause mortality. Restricted cubic splines were used to estimate the potential nonlinear relationship. Results: A total of 32,720 participants were followed up for a median time of 13.19 years, and the intake of total carbohydrates was positively associated with diabetic kidney disease (DKD) (HR 1.04, 95% CI 1.02–1.07 per 5% increase in energy intake; P = 0.005) and all-cause mortality (1.03; 1.01–1.05; P = 0.020). Intake of free sugars was positively associated with DKD (1.11; 95% CI 1.07–1.15; P < 0.001), total MCDs (1.08; 1.04–1.11; P < 0.001) and all-cause mortality (1.06; 1.03–1.10; P < 0.001). Conversely, fiber intake was inversely associated with the risk of DKD (HR 0.92, 95% CI 0.89–0.96 per 5 g/d increase; P < 0.001) and total MCDs (0.95; 0.92–0.98; P = 0.008). Starch intake was not associated with any outcomes. Free sugar displayed a J-shaped association with all-cause mortality (10.4%, P-nonlinear = 0.042) and fiber presented an L-shaped relationship with MCD (17.4 g/d, P-nonlinear = 0.033). Multi-state analysis found similar results in the trajectory from MCD-free to first MCD and death. Conclusion: Reducing free sugar intake and increasing fiber intake may help mitigate MCD risk and mortality in hyperglycemic individuals.