QTcと糖尿病のコントロール状態との関係

Relationship between the QTc and the control of blood sugar in diabetic patients

　糖尿病患者においては，高血糖およびそれに伴う代謝異常の関与も加わり，心機能低下や心電図のST-T変化を認めると報告されている^1〜6）。しかし，これらの異常も食事療法や薬物療法による高血糖の是正により，心機能は改善し心電図のST-T変化も消失すると，われわれは報告してきた^7,8）。

　一方corrected QT時間（以下QTc）に関しても数多くの報告^9,10）があり，心筋梗塞患者^11〜13）や薬剤^14,15）などにて延長すると言われている。同様に糖尿病患者においてもQTcは延長すると述べられている^16）が，糖尿病のコントロール状態との関係についての検討はない。

In order to elucidate the effect of metabolic dis-orders of diabetes mellitus on the corrected QT interval (QTc), an examination was performed at 8: 00~9: 00 a. m. after an overnight fast before and after diabetic treatment. The standard 12-lead elec-trocardiograms were recorded in 13 diabetic patients. From these tracings, the QT intervals were measured from lead II on 3 beats, then the QTcs were calcu-lated according to Bazett's formula. At the same time, the FBS and the HbA₁ were measured before and after diabetic treatment.

1) There were significant correlations between the QTc and the HbA₁:

QTc (ms)=11.8 HbA₁ (%) 268, r= 0.60, p<0.05

QTc (ms)= 13.2 HbA₁ (%) + 276, r = 0.70, p<0. 01

before and after treatment, respectively.

2) There were no significant correlations be- tween the QTc and the FBS : r=0. 41,0. 54 before and after treatment, respectively.

These results indicate that the QTc in diabetic patients are influenced by the control of blood sugar, especially HbA₁.