Is there a critical HbAlc value that predicts cardiovascular events in diabetics?

Recent evidence indicates that blood glucose is an independent continuous risk factor for cardiovascular disease, even below the diabetic threshold. Incipient abnormalities of cardiac structure and function have been observed not only in diabetics, but also in subjects with impaired glucose tolerance, in whom they may thus have an early impact.

The United Kingdom Prospective Diabetes Study (UKPDS) demonstrated that reducing glycated hemoglobin (HbAj ) from 7.9% in the conventionally treated group to 7% in the intensively treated group reduced the risk of any diabetes-related end point by 12%, diabetes-related death by 10%, all-cause mortality by 6%, myocardial infarction by 16%, and microvascular complications by 25%. A 16% reduction in the risk of combined fatal or nonfatal myocardial infarction and sudden death was observed but it was not significant; mortality, whether diabetes-related or all-cause, did not differ between the conventional and intensive groups.

In elderly Finnish patients, mortality and event rates in coronary heart disease (CHD) were lowest at HbAk levels <6% and highest at levels >7.9%. The Honolulu Heart Study and Islington Diabetes Survey observed a similar relationship between low glucose levels and a low risk of CHD. In a recent population study in elderly patients, Chae et al found a positive association between the baseline level of HbAlc and the risk of developing heart failure. There is evidence that there is an increased risk of cardiovascular disease with plasma glucose levels even lower than those considered diagnostic of diabetes (7.0 mmol/L).

The lesson from all these studies is that cardiologists must learn to view aggressive antidiabetic therapy targeted at HbA[c levels <7% as a priority, and their own role as central to their patients’ diabetic care. Further reading Breuer HWM. The postprandial blood glucose level. A new target for optimizing treatment of diabetes mellitus. Eur Heart J Suppl. 2000;2:D36-D38. Chae CU, Glynn RJ, Man son JE, et al. Diabetes predicts congestive heart failure risk in the elderly. Circulation. 1998;98(suppl l):721. UK Prospective Diabetes Study (UKPDS) Group. Intensive blood-glu-cose control with sulphonyiureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet. 1998;352:837-853. Keywords diabetes; glycated hemoglobin (HbAlc); prevention; cardiovascular event; prognosis [gallery ids=""]

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