Elevated Levels of Lipoprotein(a) Increase Cardiovascular Disease Risk in Patients with Type I Diabetes

Results obtained by a team of Swedish researchers indicated that individuals with type I diabetes were at greater risk of developing cardiovascular disease (CVD) if they had elevated levels of lipoprotein(a) in their blood.

Lipoprotein(a) [Lp(a)] consists of an LDL-like particle, and the specific protein, apolipoprotein(a), which is bound covalently to the apoB protein contained in the outer shell of the particle. Lp(a) plasma concentrations are highly heritable and mainly controlled by the LPA gene located on chromosome 6q26-27.

While previous studies had shown that high levels of Lp(a) were linked to increased risk of developing CVDs, such as myocardial infarction, stroke, and calcified aortic valve disease; the impact of Lp(a) on development of CVDs by diabetes patients had not been assessed. Thus, investigators at the Karolinska Institutet (Stockholm, Sweden) examined the association of Lp(a) and vascular complications in patients with type I diabetes mellitus.

For this study, the investigators evaluated Lp(a) and blood-sugar levels as well as the incidence of cardiovascular disease and related complications in a population of 1,860 patients with type I diabetes. The population was divided into four groups according to Lp(a) levels in nanomoles per liter (Very Low: less than 10; Low: from 10-30; Intermediate: from 30-120; High: more than 120).

Results revealed that Lp(a) levels increased with increasing age. Furthermore, patients in the high Lp(a) group had greater prevalence of CVD complications than patients in the very low Lp(a) group. Patients with type I diabetes and high Lp(a) levels had a 50% greater risk of developing some form of CVD, a 70% higher risk of coronary artery disease, and a 100% higher risk of calcified aortic valve disease, than patients with type I diabetes and low Lp(a) levels. These patients also had a 70% greater risk of protein leakage into the urine, a sign of reduced kidney function. Patients with elevated blood glucose (HbA1c) values had higher Lp(a) levels than patients with low blood glucose values.

"Our conclusion is that high levels of lipoprotein(a) in patients with type I diabetes add to the already elevated risk of developing cardiovascular disease," said first author Karin Littmann, a doctoral student in laboratory medicine at Karolinska Institutet. "The levels of these blood lipids should therefore be measured and should form part of the total risk assessment. There is currently no readily available treatment for high lipoprotein(a) levels, but the treatment of all other risk factors for cardiovascular disease should be optimized for patients with type I diabetes and high levels of lipoprotein(a).

The Lp(a)/diabetes paper was published in the December 20, 2019, online edition of the journal Diabetes Care.

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