Heterogeneous behavior of lipids according to HbA1c levels undermines the plausibility of metabolic syndrome in type 1 diabetes: data from a nationwide multicenter survey

Abstract

BackgroundCardiovascular risk factors (CVRF) may cluster in type 1 diabetes, analogously to the metabolic syndrome described in type 2 diabetes. The threshold of HbA1c above which lipid variables start changing behavior is unclear. This study aims to 1) assess the behavior of dyslipidemia according to HbA1c values; 2) detect a threshold of HbA1c beyond which lipids start to change and 3) compare the clustering of lipids and other non-lipid CVRF among strata of HbA1c individuals with type 1 diabetes.MethodsEffects of HbA1c quintiles (1st: ≤7.4%; 2nd: 7.5-8.5%; 3rd: 8.6-9.6%; 4th: 9.7-11.3%; and 5th: >11.5%) and covariates (gender, BMI, blood pressure, insulin daily dose, lipids, statin use, diabetes duration) on dyslipidemia were studied in 1275 individuals from the Brazilian multi-centre type 1 diabetes study and 171 normal controls.ResultsBody size and blood pressure were not correlated to lipids and glycemic control. OR (99% CI) for high-LDL were 2.07 (1.21-3.54) and 2.51 (1.46-4.31), in the 4th and 5th HbA1c quintiles, respectively. Hypertriglyceridemia increased in the 5th quintile of HbA1c, OR 2.76 (1.20-6.37). OR of low-HDL-cholesterol were 0.48 (0.24-0.98) and 0.41 (0.19-0.85) in the 3rd and 4th HbA1c quintiles, respectively. HDL-cholesterol correlated positively (0.437) with HbA1c in the 3rd quintile. HDL-cholesterol and insulin dose correlated inversely in all levels of glycemic control.ConclusionsCorrelation of serum lipids with HbA1c is heterogeneous across the spectrum of glycemic control in type 1 diabetes individuals. LDL-cholesterol and triglycerides worsened alongside HbA1c with distinct thresholds. Association of lower HDL-cholesterol with higher daily insulin dose is consistent and it points out to a role of exogenous hyperinsulinemia in the pathophysiology of the CVRF clustering. These data suggest diverse pathophysiological processes depending on HbA1c, refuting a unified explanation for cardiovascular risk in type 1 diabetes.

Dyslipidemia in young patients with type 1 diabetes mellitus

“…(14) and Giuffrida and cols. (17), in which they reported correlation between poor HbA1c levels and he presence of DLP, were different from the present findings.…”

The prevalence of dyslipidemia and associated factors in children and adolescents with type 1 diabetes

“…There is a relationship between dyslipidemia and high A 1C levels. Increased lipid levels as a characteristic of patients with poor metabolic control have been shown by many studies [14,[29][30][31][32]. A study by Maahs et al evaluated lipid changes during the follow-up of patients with T1D over a period of about 2 years.…”

Dyslipidemia and Diabetes: Reciprocal Impact of Impaired Lipid Metabolism and Beta-Cell Dysfunction on Micro- and Macrovascular Complications

“…However, it must be considered that glucose balance also directly impacts triglyceride metabolism. In fact, the tight correlation of lipid profile with HbA1c levels is heterogeneous across the spectrum of values of glycemic control in T1D individuals, with triglycerides worsening alongside HbA1c quintiles, as observed in a large recent nationwide multicenter survey [4]. All together, these data may, in part, explain the different results reported in the literature regarding T1D and lipid control, and questioned an unified explanation for impaired lipid metabolism in these patients.…”