Ceramides as Risk Markers for Future Cardiovascular Events and All-Cause Mortality in Long-standing Type 1 Diabetes

Abstract

Ceramides are lipid molecules involved in inflammation-related signaling. Recent studies have shown that higher amounts of specific circulating ceramides and their ratios are associated with future development of cardiovascular (CV) disease (CVD). We examined the associations between serum ceramide levels with CVD, kidney failure, and all-cause mortality in individuals with long-standing type 1 diabetes (T1D). We included 662 participants with T1D and 6-year follow-up, with a mean age of 55 years and mean diabetes duration of 33 years. Baseline serum samples were analyzed using liquid chromatography-mass spectrometry. Six predefined ceramide levels were measured, and predefined ratios were calculated. Adjusted Cox regression analyses on ceramide levels in relation to future CV events (CVE), kidney failure, and all-cause mortality were performed, with and without adjustment for age, sex, BMI, LDL, triglycerides, systolic blood pressure, HbA1c, history of CVD, smoking status, statin use, estimated glomerular filtration rate (eGFR), and urinary albumin excretion rate (UAER). The ceramide ratio cer(d18:1/18:0)/cer(d18:1/24:0) was significantly associated with risk of CVE (hazard ratio [HR] = 1.33, P = 0.01) and all-cause mortality (HR = 1.48, P = 0.01) before and after adjustments. All five investigated ceramide ratios were associated with kidney failure, before adjusting for the kidney markers eGFR and UAER. In this study, we demonstrate specific ceramides and ratios associated with 6-year cardiovascular risk and all-cause mortality in a T1D cohort. This highlights the strength of ceramide association with vascular complications and presents a new potential tool for early risk assessment if validated in other cohorts.

Article highlights: Improved tools for assessing risk for diabetes complication before onset will help in complication prevention. We investigated a set of six predefined ceramides and their ratios versus 6-year outcomes of cardiovascular events, kidney failure, and all-cause mortality in people with long-standing type 1 diabetes, using Cox regression with and without adjustment for potential confounders. We found that several ceramides and ceramide ratios associated with cardiovascular events and all-cause mortality. The ratio of cer(d18:1/18:0)/cer(d18:1/24:0) was an especially robust marker. These finding show that ceramides can be biomarkers of cardiovascular disease and all-cause mortality in individuals with long-standing type 1 diabetes.

Figure 1

Forest plot of HRs for ceramide and ratios for outcomes of CVE, kidney failure, and mortality. The crude models are unadjusted; level 1 adjusted for age, sex, BMI, LDL, triglycerides, systolic blood pressure, HbA_1c, history of CVD, smoking status and statin use; and level 2 adjusted for all the same variables as level 1, but also including eGFR and UAER. HRs are reported per doubling of the log10 ceramide.

Figure 2

Kaplan-Meier plot of (A) cer18/cer24:0 ratio and (B) LDL against CVE. High is metabolite level greater than or equal to the median; low is individuals with a metabolite level below the median.

Figure 3

Heatmap of ceramides correlation to possible CVE confounders, presented as correlations coefficients from Pearson correlation.

Figure 4

Forest plot of HRs for ceramide and ratios for CVE separated by albuminuria status. Normoalbuminuria is defined as <30 mg/g, moderately increased is between 30 and 299 mg/g, and severely increased is ≥300 mg/g. These models are unadjusted crude models. HRs are reported per doubling of the log10 ceramide.