Lipid variability and risk of microvascular complications in patients with diabetes: a systematic review

Dyslipidemia is a common presentation in individuals with type 2 diabetes mellitus (T2DM), even among those with good glycemic control. Indeed, individuals with T2DM have been found to have abnormally high levels of triglycerides, decreased high-density lipoproteins (HDL), and modest or normal levels of low-density lipoproteins (LDL).In a cross-sectional study of T2DM patients, the researchers found the prevalence of hypertriglyceridemia, abnormal HDL levels (130 mg/dL) to be 61.9%, 54.3%, and 8.9%, respectively,2 similar to the findings of other studies. These abnormal lipid levels have been implicated in the development of several diabetes-related complications including diabetic macrovascular and microvascular disease. Meanwhile, higher variabilities in lipid variables have also been found to be detrimental to health among populations with or without diabetes. For example, in a study of approximately 1000 participants with clinical presentation of coronary disease involved in the Treating to New Target trial, greater variability in HDL, triglyceride, and LDL was found to be associated with cardiovascular events.Also, a recent study of over 10 000 T2DM patients showed that higher variability in HDL, LDL, and total cholesterol appeared to increase the risk of all-cause mortality whereas greater variability in HDL was associated with noncardiovascular deaths.However, few of these studies were on the relationship between lipid variability and diabetic microvascular complications.Diabetic microvascular complications, which comprise nephropathy, neuropathy, and retinopathy, together contribute hugely to the burden of diabetic-related morbidity and mortality.Reports show that during a lifetime, about 20%-40% of patients with T2DM would develop diabetic kidney disease,20 up to 50% would eventually develop diabetic neuropathy,21 and 10% are likely to develop diabetic retinopathy.