Insulin Resistance Index and Proatherogenic Lipid Indices in the Offspring of People with Diabetes

Abstract

Background: Diabetes mellitus and cardiovascular diseases significantly contribute to medical morbidity and mortality worldwide, especially in developing countries like Nigeria. Insulin resistance, a characteristic finding of type 2 diabetics and their offspring, is associated with an abnormal lipid metabolism and cardiovascular disease. Aims: This study therefore aims to determine the pattern of lipid biomarkers of atherogenesis and their relationship with insulin resistance index in young people with a family history of diabetes mellitus. Methods: This is a cross-sectional study carried out among 150 apparently healthy young adults between 18 and 25 years of age, including 76 with a family history of diabetes mellitus in first- and/or second-degree relatives (YWFH) and 74 with no family history of diabetes mellitus (YWoFH). Anthropometric characteristics, insulin resistance index, plasma glucose, fasting lipid profile (plasma total cholesterol, triglycerides [TG], high-density lipoprotein cholesterol, low-density lipoprotein cholesterol), and serum levels of insulin, lipoprotein(a) [Lp(a)], apolipoprotein B (ApoB), apolipoprotein A-1 (ApoA-1), and ApoB/ApoA-1 ratios were compared in the 2 groups. Plasma glucose, total cholesterol, high-density cholesterol, and TG were measured using standard methods. The Friedewald equation was used to calculate low-density cholesterol. Serum insulin, Lp(a) levels, ApoB, and ApoA-1 were also measured using standard assays. The insulin resistance index was determined using homeostatic model assessment (HOMA). Statistical analysis was performed using SPSS version 20.0. Comparisons between variables were performed using the Mann-Whitney U test, and correlations between variables were performed using Spearman rank correlation coefficients. The level of significance was set at p < 0.05. Results: Offspring of diabetics (YWFH) had a significantly higher median BMI (p = 0.015), waist-to-hip ratio (WHR; p = 0.002), insulin resistance index (p = 0.038), total cholesterol (p = 0.017), TG (p = 0.004), Lp(a) (p = 0.045), ApoB (p = 0.002), and ApoB/ApoA-1 ratio (p = 0.001) than the age-matched control group with no family history of diabetes mellitus (YWoFH). There was no correlation between the insulin resistance index and each of the lipid biomarkers of atherogenesis except Lp(a), with which it was negatively correlated. Conclusion: This study demonstrates that a positive family history of type 2 diabetes mellitus is associated with a higher insulin resistance index and elevated atherogenic lipid indices; thus, a positive family history of diabetes mellitus in first or second-degree relatives when the index person is not diabetic confirms a significant cardiovascular risk.