Sweet Heart? Fasting Blood Glucose and Cardiovascular Disease Risk
By Dr. Dicken Weatherby & Beth Ellen DiLuglio, MS, RDN, LDN
What do fasting blood glucose and cardiovascular disease have in common, you ask? Everything that is risky to the heart.
Accumulating research identifies blood glucose levels above the optimal range as a risk factor for cardiovascular disease even in those with no prior history of a cardiovascular event.
That is big news but should not be surprising when considering cardiovascular disease (CVD) is the number one cause of death in those with diabetes.
Assessing blood glucose and identifying prediabetes (impaired fasting glucose) and pre-prediabetes will provide practitioners with data to assess cardiovascular disease risk as well.
According to the American Diabetes Association, the American Association of Clinical Endocrinologists, and the Endocrine Society, a fasting blood glucose (FBG) below 100 mg/dL (5.6 mmol/L) is normal; FBG of 100-125 mg/dL (5.6 and 6.9 mmol/L) indicates prediabetes or impaired fasting glucose; and a FBG 126 or greater is diagnostic for diabetes.
However, a dive into the past reveals 1999 results of a prospective study demonstrating that non-diabetic individuals with a FBG of 86-109 mg/dL (4.8-6.1 mmol/L) had a “significantly higher mortality rate from cardiovascular diseases compared to the three lowest quartiles... even after adjusting for age, smoking habits, serum lipids, blood pressure, forced expiratory volume in 1 s, and physical fitness.”
Here we see the negative effects of fasting blood glucose levels accepted as “normal” at the time. Research into the link between elevated FBG and CVD continues today and defines even more stringent cutoffs for what is acceptable.
Results of research published in 2019 assessed CVD risk stratified by FBG levels in those with no history of a cardiac event. A study of 19,630 individuals indicated that incidence for each CVD end point was lowest among those with fasting blood glucose of less than 90 mg/dL (5.0 mmol/L) and highest among those meeting criteria for diabetes. If left unchecked, conversion of prediabetes to diabetes was associated with a 1.3-3.6-fold increase in cardiovascular risk including coronary heart disease and stroke. 
Additional research published in 2019 reveals that risk of major cardiovascular events is lowest for non-diabetic individuals with a FBG below 79 mg/dL (4.4 mmol/L). Risk begins to increase in those with FBG of 79-99 mg/dL (4.4-5.5 mmol/L) and rises linearly for those with FBG above 100 mg/dL (5.6 mmol/L).
Researchers offer a stark warning to individuals with prediabetes who don’t adopt effective lifestyle changes including a healthy diet, nutrition intervention, and adequate physical activity: Most of those individuals will have type 2 diabetes within 10 years. We now know that their risk of developing cardiovascular disease is imminent as well.
A healthy diet incorporates an abundance of fresh unprocessed foods; fruits and vegetables; herbs, spices, nuts, and seeds; unprocessed high-quality protein; minimally processed complex carbohydrates such as whole grains, legumes, and starchy vegetables; and plentiful amounts of purified water. Targeted micronutrient nutrition support may be indicated, especially for those with underlying metabolic disorders such as cardiovascular disease and the full spectrum of blood glucose dysregulation.
Remember, an ounce of prevention is worth a pound of cure.
Strive for a healthy optimal fasting blood glucose of 75-86 mg/dL (4.2-4.8 mmol/L)
Be well… there is a long road ahead.
- American Diabetes Association. 2. Classification and Diagnosis of Diabetes: Standards of Medical Care in Diabetes-2020. Diabetes Care. 2020 Jan;43(Suppl 1):S14-S31.[R]
- American Association of Clinical Endocrinologists. Screening and Monitoring of Prediabetes Retrieved April 25, 2020 [R]
- The Endocrine Society Hormone Health Network. Prediabetes. Retrieved April 25, 2020 [R]
- Bjørnholt JV, Erikssen G, Aaser E, et al. Fasting blood glucose: an underestimated risk factor for cardiovascular death. Results from a 22-year follow-up of healthy nondiabetic men. Diabetes Care. 1999 Jan;22(1):45-9. [R]
- Bancks MP, Ning H, Allen NB, et al. Long-term Absolute Risk for Cardiovascular Disease Stratified by Fasting Glucose Level. Diabetes Care. 2019 Mar;42(3):457-465. Doi: 10.2337/dc18-1773. Epub 2019 Jan 7. [R]
- Jung HH, Lee S. Optimal fasting glucose levels with regard to cardiovascular and mortality outcomes in people treated with or without antidiabetic medication. Diabetes Obes Metab. 2020 Feb;22(2):243-253. [R]
- Tuso P. Prediabetes and lifestyle modification: time to prevent a preventable disease. Perm J. 2014 Summer;18(3):88-93. [R]