Lipoprotein(a)-activated immunity, insulin resistance and new-onset diabetes

ABSTRACT

Objectives: Some evidence suggests that serum lipoprotein[Lp](a) may be inversely linked to type-2 diabetes. We aimed to determine in nondiabetic people the relationship of serum [Lp](a) with insulin resistance and new-onset diabetes (NOD).

Materials and methods: Population-based middle-aged adults (n = 1685) were categorized by fasting glucose and stratified to gender, having excluded prevalent diabetic subjects. NOD (n = 90) occurred over a median 5 years’ follow-up.

Results: Subjects that subsequently developed NOD, derived both from the normoglycemia and impaired fasting glucose (IFG) groups,were distinguished, among others, primarily by significantly elevated serum gamma glutamyltransferase, reduced Lp(a) (by 31%) and, compared to IFG, by low total cholesterol levels. Partial correlation of Lp(a) with homeostatic model assessment (HOMA) was inverse in normoglycemic men; such correlation, neutral in normoglycemic women, proved inverse in IFG (r = −0.17). Circulating Lp(a) in individuals with paired measures increased significantly (1.55-fold) in the period from baseline up to NOD. Multivariable-adjusted logistic regression analysis for NOD in combined sexes indicated independent and additive prediction by serum Lp(a), albeit inverse in direction (RR 0.84, [95%CI 0.72; 0.97]).

Conclusion: Lp(a) is significantly reduced in the period preceding NOD and is inversely associated with HOMA index, observations consistent with underlying autoimmune activation.

KEYWORDS:

• Autoimmune activation
• diabetes
• type-2
• impaired fasting glucose
• insulin resistance
• lipoprotein(a)

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Additional information

Funding

The Turkish Society of Cardiology and the Turkish automotive company TOFAŞ, Istanbul, are acknowledged for support to the Turkish Adult Risk Factor study.