Serum Levels of Acylcarnitines Are Altered in Prediabetic Conditions

Objective: The role of mitochondrial function in the complex pathogenesis of type 2 diabetes is not yet completely understood. Therefore, the aim of this study was to investigate serum concentrations of short-, medium-and long-chain acylcarnitines as markers of mitochondrial function in volunteers with normal, impaired or diabetic glucose control. Methods: Based on a 75 g oral glucose tolerance test, 1019 studied subjects were divided into a group with normal glucose tolerance (NGT; n = 636), isolated impaired fasting glycaemia (IFG; n = 184), impaired glucose tolerance (IGT; n = 87) or type 2 diabetes (T2D; n = 112). Serum concentrations of free carnitine and 24 acylcarnitines were measured by mass spectrometry. Results: Serum levels of acetylcarnitine (C2), propionylcarnitine (C3), octanoylcarnitine (C8), malonylcarnitine/hydroxybutyrylcarnitine (C3DC+C4OH), hexanoylcarnitine (C6), octenoylcarnitine (C8: 1), decanoylcarnitine (C10), decenoylcarnitine (C10: 1), dodecanoylcarnitine (C12), tetradecenoylcarnitine (C14: 1), tetradecadienylcarnitine (C14: 2), hydroxytetradecanoylcarnitine (C14OH), hydroxyhexadecanoylcarnitine (C16OH) and octadecenoylcarnitine (C18: 1) were significantly different among the groups (all p<0.05 adjusted for age, gender and BMI). Between the prediabetic states C14: 1, C14: 2 and C18: 1 showed significantly higher serum concentrations in persons with IGT (p<0.05). Compared to T2D the IFG and the IGT subjects showed lower serum concentrations of malonylcarnitine/hydroxybutyrylcarnitine (C3DC+C4OH) (p<0.05). Conclusion: Alterations in serum concentrations of several acylcarnitines, in particular tetradecenoylcarnitine (C14: 1), tetradecadienylcarnitine (C14: 2), octadecenoylcarnitine (C18: 1) and malonylcarnitine/hydroxybutyrylcarnitine (C3DC+C4OH) are associated not only with T2D but also with prediabetic states.