Association of glycaemia with lipids in adults with type 1 diabetes: modification by dyslipidaemia medication

Abstract

Aims/hypothesis: Hyperglycaemia and dyslipidaemia are common metabolic abnormalities in adults with type 1 diabetes and both increase cardiovascular disease (CVD) risk. The hypothesis of this study was that change in HbA(1c) over 6 years would be associated with change in fasting lipids in adults with type 1 diabetes.

Methods: The Coronary Artery Calcification in Type 1 Diabetes (CACTI) study examined 652 patients with type 1 diabetes (54% female); 559 and 543 had follow-up visits at 3 and 6 years. Baseline age (mean ± SD) was 37 ± 9 years, diabetes duration 23 ± 9 years, and HbA(1c) 8.0 ± 1.3%. Use of dyslipidaemia medication was 17%, 32%, and 46% at the three visits. Separate longitudinal mixed models were fitted to examine the relationship between change in HbA(1c) and change in fasting total cholesterol (TC), HDL-cholesterol (HDL-c), LDL-cholesterol (LDL-c), log triacylglycerols (TG), and non-HDL-cholesterol (non-HDL-c). Because of an interaction between dyslipidaemia medication use and association of HbA(1c) with lipids, results were stratified by dyslipidaemia medication use.

Results: Among patients not using dyslipidaemia medication, a higher HbA(1c) was associated with significantly worse levels of the lipids TC, LDL-c, TG and non-HDL-c (per 1% change in HbA1c, TC 0.101 mmol/l, 95% CI 0.050, 0.152; LDL-c 0.103 mmol/l, 95% CI 0.058, 0.148; TG 0.052 mmol/l, 95% CI 0.024, 0.081; and non-HDL-c 0.129 mmol/l, 95% CI 0.078, 0.180) but not HDL-c (-0.20 mmol/l, 95% CI -0.047, 0.007). The associations between HbA(1c) and any lipid outcome among those on dyslipidaemia medication were in the same direction, but attenuated compared with persons not on medication.

Conclusions/interpretation: Change in HbA(1c) is significantly associated with change in fasting lipids, but dyslipidaemia medications may be required to optimise lipid and cardiovascular health.

Conflict of interest statement

Duality of interest D. M. Maahs has research support from Merck for a separate trial of dyslipidaemia medications in adolescents with type 1 diabetes. None of the other authors has a duality of interest associated with this manuscript.

Figures

Fig. 1

Longitudinal association of change in lipid per 1% change in HbA1c for the basic model (adjusted for sex, visit, race/ethnicity, diabetes duration, baseline HbA1c and baseline lipid [model-specific] and time-varying age, change in HbA1c, and change in HbA1c×visit interaction). Grey bars, participants receiving no lipid medication; black bars, participants receiving lipid medication. ***p<0.001 for dyslipidaemia medication status for change per 1% increase in HbA1c. aEstimated change in TG from a starting level of 0.93 mmol/l