Lp(a) concentration and polymorphic size are not associated with new onset diabetes in individuals with prediabetes

Observational studies in the general population suggest that low concentrations of lipoprotein (a) [Lp(a)] are associated with an increased risk of type 2 diabetes. Here, we aim to determine whether Lp(a) plasma concentration and Kringle-IV (K-IV) repeat polymorphism were associated with new-onset diabetes (NOD) in individuals with prediabetes.

IT-DIAB is an observational, prospective study including 303 participants with impaired fasting glucose (fasting plasma glucose [FPG]: 110-125 mg/dl) followed annually for 5 years. The primary endpoint was the development of NOD, defined as a first FPG value ≥ 126 mg/dl during follow-up. Lp(a) concentrations were measured by immunoturbidimetry, apo(a) concentrations and the number of K-IV domains by mass spectrometry. Survival analyses for NOD were modeled using Kaplan-Meier curves and a multivariable Cox model, after binarization on threshold values of Lp(a) or K-IV.

Among the participants, 113 (37%) developed NOD during follow-up. The concentrations of Lp(a) and the number of K-IV domains were not significantly different according to NOD status. Similarly, the percentage of patients with a non-detectable (≤ 7 nmol/l) or elevated (>125 nmol/l) Lp(a) concentration was similar between those with or without NOD: 68.1 vs 63.7% (P = 0.46) and 8.8 vs 8.9% (P > 0.99), respectively. Kaplan-Meier curves and Cox models did not show any association between Lp(a) concentration (threshold 7 nmol/l and 125 nmol/l) or number of K-IV domain (threshold 23) and the risk of NOD.

In a high-risk population, Lp(a) concentration or polymorphic size do not appear to be substantially associated with type 2 diabetes risk.