In diabetics where range of glucose levels and level of risk for various
heart related disorders has been studied in depth, any elevated level
above the normal range presents increased risk.  The risk increases as
the glucose level increases.

In the same vein:

Ann Intern Med 1998 Apr 1;128(7):524-33

Metabolic risk factors worsen continuously across the spectrum of
nondiabetic glucose tolerance. The Framingham Offspring Study.

Meigs JB, Nathan DM, Wilson PW, Cupples LA, Singer DE
Massachusetts General Hospital, Harvard Medical School, Boston
University School of Public Health, 02114, USA. jmeigs@sol.mgh.harvard.edu

BACKGROUND: Categorical definitions for glucose intolerance imply that
risk thresholds exist, but metabolic risk for type 2 diabetes mellitus
or cardiovascular disease may increase continuously as glucose
intolerance increases. OBJECTIVE: To examine the distributions of the
following metabolic risk factors across the spectrum of glucose
tolerance: overall and central obesity, hypertension, low levels of
high-density lipoprotein cholesterol, and increased triglyceride and
insulin levels. DESIGN: Cross-sectional analysis. SETTING: The
community-based Framingham Offspring Study. PARTICIPANTS: 2583 adults
without previously diagnosed diabetes. MEASUREMENTS: Clinical data;
fasting glucose, insulin, and lipid levels; and glucose and insulin
levels taken 2 hours after oral challenge were collected from 1991 to
1993. Glucose tolerance was determined by 1980 World Health Organization
criteria. Patients with normal glucose tolerance were categorized into
quintiles of fasting glucose. The distributions of each metabolic risk
factor and the metabolic sum of the six risk factors were assessed
across seven categories from the lowest quintile of normal fasting
glucose level through impaired glucose tolerance and previously
undiagnosed diabetes. RESULTS: The mean age of patients was 54 years
(range, 26 to 82 years); 52.7% of patients were women. Glucose tolerance
testing found that 12.7% of patients had impaired glucose tolerance and
4.8% had previously undiagnosed diabetes. Multivariable-adjusted mean
measures of risk factors and odds ratios for obesity, elevated
waist-to-hip ratio, hypertension, low levels of high-density lipoprotein
cholesterol, elevated triglyceride levels, and hyperinsulinemia showed
continuous increases across the spectrum of nondiabetic glucose
tolerance. Although a threshold effect near the upper range of
nondiabetic glucose tolerance could not be ruled out for triglyceride
levels in men and for insulin levels 2 hours after oral challenge in men
and women, no other metabolic risk factors showed clear evidence of
thresholds for increased risk. CONCLUSIONS: Metabolic risk factors for
type 2 diabetes mellitus and for cardiovascular disease worsen
continuously across the spectrum of glucose tolerance categories,
beginning in the lowest quintiles of normal fasting glucose level.

PMID: 9518396, UI: 98175274

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Blood Glucose Concentration Linked to>Cardiovascular Risk in Nondiabetic
Men>
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WESTPORT,>CT (Reuters Health) Jan 04 - Increased glycated hemoglobin
(HbA1c)>concentrations are predictive of cardiovascular mortality among
all men,>not only those with diabetes, according to a report in the
British>Medical Journal for January 6.

Dr. Kay-Tee Khaw and colleagues, from>the University of Cambridge
School of Clinical Medicine, UK, collected>data on all-cause mortality
and cardiovascular mortality in 4662 men, 45>to 79 years of age, who
participated in the Norfolk UK cohort of the>European Prospective
Investigation into Cancer and Nutrition>(EPIC-Norfolk). At baseline,
from 1995 to 1997, HbA1c was measured and>the subjects were followed
until December 1999.

As expected, Dr.>Khaw's group found that diabetic men had increased
mortality for all>causes, cardiovascular disease and ischemic disease.
They also noted that>HbA1c concentrations were "continuously related to
subsequent all-cause,>cardiovascular, and ischemic mortality through
the whole population." The>lowest mortality rates were associated with
HbA1c concentrations below>5%.

Further, the group noted that a 1% increase in HbA1c was>associated
with a 28% increased risk of death, which was independent of>age, blood
pressure, cholesterol, body mass index and>smoking.

"Eighteen percent of the population excess mortality risk>associated
with a HbA1c concentration of 5% or more occurred in men with>diabetes,
but 82% occurred in men with concentrations of 5% to 6.9% (the>majority
of the population)," Dr. Khaw and colleagues point>out.

The researchers propose that an elevated concentrations of>HbA1c is a
marker for greater absolute risk among all men, and>"preventive
treatment with blood pressure- or cholesterol-lowering drugs>should be
considered in such patients."

They point out that if>the population of nondiabetic men was able to
lower its HbA1c>concentration by 0.1%, total mortality could be reduced
by 5%, and if the>concentration could be lowered by 0.2%, then total
mortality could be>reduced by 10% in this population.
--

Annals of Internal Medicine, 9/21/2004, Vol 141, no 6, 413-420
Association of Hemoglobin A1c with Cardiovascular Disease and Mortality
in Adults: The European Prospective Investigation into Cancer in Norfolk
Kay-Tee Khaw, MBBChir FRCP; Nicholas Wareham, MBBS, FRCP; Sheila
Bingham, PhD; Robert Luben, BSc; Ailsa Welch, BSc; and Nicholas Day, PhD

In men and women, the relationship between hemoglobin A1c and
cardiovascular disease (806 events) and between hemoglobin A1c and
all-cause mortality (521 deaths) was continuous and significant
throughout the whole distribution. The relationship was apparent in
persons without known diabetes. Persons with hemoglobin A1c
concentrations less than 5% had the lowest rates of cardiovascular
disease and mortality. An increase in hemoglobin A1c of 1 percentage
point was associated with a relative risk for death from any cause of
1.24 (95% CI, 1.14 to 1.34; P < 0.001) in men and with a relative risk
of 1.28 (CI, 1.06 to 1.32; P < 0.001) in women. These relative risks
were independent of age, body mass index, waist-to-hip ratio, systolic
blood pressure, serum cholesterol concentration, cigarette smoking, and
history of cardiovascular disease.

Arch Intern Med. 2005;165:1910-1916. Glycemic Control and Coronary Heart
Disease Risk in Persons With and Without Diabetes. The Atherosclerosis
Risk in Communities Study. Elizabeth Selvin, PhD, MPH; Josef Coresh, MD,
PhD; Sherita H. Golden, MD, MHS; Frederick L. Brancati, MD, MHS; Aaron
R. Folsom, MD; Michael W. Steffes, MD, PhD

In nondiabetic adults, HbA1c level was not related to CHD risk below a
level of 4.6% but was significantly related to risk above that level
(P<.001). In diabetic adults, the risk of CHD increased throughout the
range of HbA1c levels. In the adjusted model, the Risk Ratio of CHD for
a 1 percentage point increase in HbA1c level was 2.36 (95% CI,
1.43-3.90) in persons without diabetes but with an HbA1c level greater
than 4.6%. In diabetic adults, the Risk Ratio was 1.14 (95% CI,
1.07-1.21) per 1 percentage point increase in HbA1c across the full
range of HbA1c values.