Elevated blood sugar in people without a prior diagnosis of diabetes raises the risk of premature death, results of a study show.

Only a few prospective studies have looked at associations between blood sugar levels among subjects initially free of diabetes and subsequent risk of death, Dr. Naomi Brewer, of Massey University, Wellington, New Zealand, and colleagues point out in the journal Diabetes Care.

Hemoglobin A1C testing - a standard way to measure blood sugar - was offered to people without diabetes during a screening program for hepatitis B in a region of New Zealand from 1999 to 2001. Mortality risk was examined to the end of 2004 in these subjects.

Among a total of 47,904 individuals, whose average age was 38 years, 815 died during the median follow-up of 4.4 years.

Brewer’s team found that the risk of premature death rose in tandem with blood sugar levels. The risk of death increased steadily from the A1C “reference category” (4.0% to less than 5.0%) to the highest A1C category (7.0% or higher).

Strong associations were seen between elevated blood sugar and death from endocrine, nutritional, metabolic, and immunity disorders. Blood sugar was also strongly associated with death from diseases of the circulatory system. Weaker associations were observed between increasing blood sugar and deaths from cancer and other and unknown causes.

The investigators note that this is the largest study conducted to date of A1C levels and subsequent risk of mortality. “It confirms previous findings that A1C levels are strongly associated with subsequent mortality in both men and women who have not been diagnosed with diabetes.”

SOURCE: Diabetes Care, June 2008.