Inconvenient relationship of haemoglobin A1c level with endothelial function in type 2 diabetes in a cross-sectional study.

BMJ open 2021 Jun 09

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The aim of this study was to determine the relationship of haemoglobin A1c (HbA1c) level with flow-mediated vasodilation (FMD) and nitroglycerine-induced vasodilation (NID) in patients with type 2 diabetes. Cross-sectional study. 22 university hospitals and affiliated clinics in Japan. 1215 patients with type 2 diabetes including 349 patients not taking antidiabetic drugs. We evaluated FMD and HbA1c level. All patients were divided into four groups based on HbA1c level: <6.5%, 6.5%-6.9%, 7.0%-7.9% and ≥8.0%. An inverted U-shaped pattern of association between HbA1c level and FMD was observed at the peak of HbA1c of about 7%. FMD was significantly smaller in the HbA1c <6.5% group than in the HbA1c 6.5%-6.9% group and HbA1c 7.0%-7.9% group (p<0.001 and p<0.001), and FMD values were similar in the HbA1c <6.5% group and HbA1c ≥8.0% group. There were no significant differences in NID values among the four groups. After adjustments for confounding factors, FMD was significantly smaller in the HbA1c <6.5% group than in the HbA1c 6.5%-6.9% and HbA1c 7.0%-7.9% group (p=0.002 and p=0.04). In patients not taking antidiabetic drugs, FMD was also significantly smaller in the HbA1c <6.5% group than in the HbA1c 6.5%-6.9% group and HbA1c 7.0%-7.9% group (p<0.001 and p=0.02), and there were no significant differences in NID values among the four groups. These findings suggest that there is an inverted U-shaped pattern of association between FMD and HbA1c and that a low HbA1c level of <6.5% is associated with endothelial dysfunction. UMIN000012950, UMIN000012951, UMIN000012952 and UMIN000003409. © Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Citation

Takayuki Yamaji, Takahiro Harada, Yu Hashimoto, Yuji Takaeko, Masato Kajikawa, Yiming Han, Tatsuya Maruhashi, Shinji Kishimoto, Haruki Hashimoto, Yasuki Kihara, Eisuke Hida, Kazuaki Chayama, Chikara Goto, Farina Mohamad Yusoff, Ayumu Nakashima, Yukihito Higashi. Inconvenient relationship of haemoglobin A1c level with endothelial function in type 2 diabetes in a cross-sectional study. BMJ open. 2021 Jun 09;11(6):e045415