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Open Access Original investigation

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

Fernando MA Giuffrida12*, Alexis D Guedes1, Eloa R Rocco2, Denise B Mory2, Patricia Dualib2, Odelisa S Matos1, Reine M Chaves-Fonseca1, Roberta A Cobas3, Carlos Antonio Negrato4, Marilia B Gomes3, Sergio A Dib2 and Brazilian Type 1 Diabetes Study Group (BrazDiab1SG)

Author Affiliations

1 CEDEBA-Centro de Endocrinologia do Estado da Bahia, Salvador, Brazil

2 Diabetes Center, Federal University of Sao Paulo, Sao Paulo, Brazil

3 Rio de Janeiro State University, Rio de Janeiro, Brazil

4 Associação de Diabéticos de Bauru, Bauru, Brazil

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Cardiovascular Diabetology 2012, 11:156  doi:10.1186/1475-2840-11-156

Published: 27 December 2012

Abstract

Background

Cardiovascular 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.

Methods

Effects 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.

Results

Body 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.

Conclusions

Correlation 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.

Keywords:
Type 1 diabetes; Metabolic syndrome; Dyslipidemia; Cardiovascular risk factor