Lipid Abnormalities as Predictors of Glycemic Control in Type 2 Diabetes Mellitus: A Systematic Review

Abstract

Type 2 diabetes mellitus (T2DM) is characterized by persistent disturbances in glucose metabolism and is frequently accompanied by an atherogenic pattern of dyslipidemia. Although glycated hemoglobin (HbA1c) remains the principal marker of long-term glycemic control, increasing evidence suggests that abnormalities in circulating lipids may be associated with poor glycemic status and could provide complementary information regarding underlying metabolic dysfunction. This systematic review evaluates the relationship between lipid abnormalities and glycemic control in adults with T2DM, with particular emphasis on triglycerides, total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), non-HDL cholesterol, and lipid-derived ratios. Relevant observational and longitudinal studies evaluating lipid parameters in relation to HbA1c or other established measures of glycemic control were considered. Particular attention was given to the direction and consistency of associations, the ability of baseline lipid abnormalities to predict subsequent glycemic outcomes, and the influence of potential confounding factors including obesity, diabetes duration, medication use, renal function, lifestyle, and lipid-lowering therapy. Across the available literature, poor glycemic control is frequently accompanied by hypertriglyceridemia, reduced HDL-C, and abnormalities in atherogenic lipid indices, whereas associations involving total cholesterol and LDL-C appear less uniform. However, much of the evidence is cross-sectional, limiting the ability to distinguish lipid abnormalities as true predictors from metabolic correlates of inadequate glycemic control. The clinical utility of lipid parameters for predicting future HbA1c therefore remains uncertain. Prospective studies incorporating standardized lipid measurements, repeated HbA1c assessment, treatment exposure, and multivariable adjustment are required to determine whether specific lipid abnormalities provide independent predictive information beyond established determinants of glycemic control. Keywords: Type 2 diabetes mellitus; glycemic control; HbA1c; dyslipidemia; triglycerides.