Factors associated with Elevated Plasma levels of Liprotein (a) in indegenous black Zambians with Diabetes Mellitus type 2 in the outpatient medical clinic at the University Teaching Hospital,Lusaka,Zambia

Abstract

Introduction: Diabetes mellitus (DM) is an established risk factor for cardiovascular disease (CVD) and is considered to be a CVD equivalent. Lipoprotein(a) [Lp(a)] is an independent risk factor for cardiovascular diseases. Since Diabetes Mellitus Type 2 (T2DM) patient numbers continue to rise, and since patients continue to present with cardiovascular disease-related complications, it is possible that some of these patients have high plasma levels of Lp(a). The aim of the study was to investigate the plasma levels of Lp(a) in T2DM patients and also to assess the factors that may be associated with the plasma levels of Lp(a) among indigenous black Zambians with T2DM. Materials and methods: We conducted a cross sectional study that enrolled 155 participants, 79 T2DM patients attending the outpatient medical clinic of the University Teaching Hospital and 76 community-based healthy individuals. A short questionnaire was used to record the social demographic characteristics and anthropometric measurements. 4ml of venous blood was collected from which all the analytes were measured. The factors that were assessed for association with Lp(a) included; social demographic characteristics, social economic status, duration of illness, dietary composition, physical fitness, BMI, fasting blood sugar (FBS), renal function, hepatic function, acute phase response, lipid profile, and glycaemic control. Therefore the variables that were measured were as follows; Age, sex, marital status, occupation, residence, dietary fat content, dietary carbohydrate source, dietary protein source, frequency of exercise, BMI, FBS, ALT, urea, creatinine, C-reactive protein, Triglycerides, total cholesterol, low density lipoprotein, high density lipoprotein, HbA1c and lipoprotein(a) respectively. The data were expressed as median (interquartile range). The Mann-Whitney U test was used to compare the median values between the two groups of the study participants (Diabetics and healthy individuals) for continuous variables, the Wilcoxon rank-sum test or Kruskal-Wallis test for the ordinal data whereas the Chi-squared test was used to compare the proportions for the nominal data. SPSS version 21(IBM) was used to perform a multiple linear regression analysis to identify the *9/et of variables that would best predict the plasma levels of Lp(a) Results: The median plasma levels of Lp(a) in the diabetics (20.0 (11.8-37.4)mg/dl) was significantly higher (p<0.001,) than the healthy individuals (13.6 (9.4-21.5)mg/dl). 17 % of the diabetics had plasma levels of Lp(a) higher than 30 mg/dl. Of all the independent variables assessed, the results showed that glycemic control (HbA1c), FBS (glucose) triglycerides and residence were significant (p<0.001, p=0.030, p=0.040, p= 0.004 respectively) predictors of plasma levels of Lp(a). The linear relationships showed that the plasma levels of Lp(a) had a positive relationship with HbA1c (r=5.220) and FBS (r=0.660) whereas the relationship with triglycerides (r= -4.794) and residence (r= -7.165) were inverse Conclusion: . The plasma levels of Lp(a) in the T2DM patients were significantly higher than the non-diabetic healthy individuals. Glycemic control (HbA1c) , triglycerides (TG), fasting blood glucose (FBS) and social economic status (medium density residence) were predictors of serum levels of Lp(a).