Insulin resistance and metabolic syndrome are at the heart of both type 2 diabetes and cardiovascular disease.

Dr. SM Grundy, MD, PhD, at the University of Texas Southwestern Medical Center, believes that, “approximately one-third of an apparently healthy population is sufficiently insulin-resistant to be at increased risk to develop type 2 diabetes, cardiovascular disease, high blood pressure, polycystic ovary disease, nonalcoholic liver disease and others.” 

Focusing on metabolic syndrome, he states, will have the greatest impact on reducing the risk for cardiovascular disease.

Metabolic syndrome is usually defined as: waist circumference over 35 inches for women and 40 for men, fasting glucose over 100 mg/dL, blood pressure over 130/85, triglycerides over 150 mg/dL, HDL cholesterol less than 50 mg/dL for women and less than 40 mg/dL for men. Often, proinflammatory and prothrombotic factors are also considered, measured as elevated hs-CRP and fibrinogen, respectively.
To recognize the presence of metabolic syndrome and dysfunctional insulin signaling - before organs are damaged and a definitive disease takes place - Dr. Jeff Bland, PhD, FACN, FACB suggests that the best early-stage marker associated with insulin resistance is the shift of the apolipoprotein B and apoliprotein A-1 levels in the serum.

Apolipoprotein B is the primary apolipoprotein of low density lipoproteins (LDL or "lousy cholesterol"), which carries cholesterol to tissues.  Apolipoprotein A-I is the major protein component of high density lipoprotein (HDL or “good cholesterol) in plasma that promotes cholesterol being excreted out of the body by the liver.  These lipoproteins are affected by not only genes, but by diet, lifestyle, and environmental factors.
It has been well-documented that an elevated apolipoprotein B to apolipoprotein A-1 ratio is an important determinant of cardiovascular disease risk  - independent of total serum cholesterol levels.

Dr Bland suggests that Apo B/apo A-1 ratio may be the most useful summary index of cardiovascular risk and that it is more helpful than the conventionally used LDL-cholesterol measurements and various other lipid ratios. The advantage also of the apo B/apo A-1 ratio is that it can be determined in non-fasting blood, unlike other cholesterol tests.

The lower the ratio, the lower the risk.   A ratio of apo B/apo A-1 of 0.7 or lower would be considered a lower risk, whereas a ratio of 0.8 or higher would represent an increased risk.

More importantly, the apo B/apo A-1 is a very sensitive indicator of the change in insulin signaling and provides an early warning of the risk associated with metabolic syndrome, often leading to heart disease and type 2 diabetes.