Metabolic Syndrome in an Elderly Population is More Linked to Insulin Resistance Than to Obesity

In the United States cardiovascular disease (CVD) accounts for 1 in every 2.8 deaths and is the leading cause of death among men and women 65 years or older (1). Studies have shown that the risk for cardiovascular disease is higher in individuals with the Metabolic Syndrome (2). Metabolic Syndrome (MBS) is defined by the Adult Treatment Panel III (ATP III) guidelines as a group of risk factors that includes 3 or more of the following: abdominal obesity, hypertriglyceridemia, low high-density lipoprotein (HDL) cholesterol, high blood pressure, and high fasting glucose (3). These factors place individuals at increased risk for the development of both cardiovascular disease (CVD) and diabetes mellitus (3). It is commonly held that insulin resistance is the driving force for the development of the MBS.

Although there is a significant increase in incidence of MBS in the elderly, there are few studies that specifically examined MBS in that population. The prevailing opinion is that the strikingly high prevalence of the MBS in the elderly is due to concurrent obesity - i.e., the population gains weight as it ages, and development of the MBS accompanies the weight gain.

However, while it is true that becoming obese may decrease insulin sensitivity, it has also been demonstrated that not all obese individuals are insulin resistant. Some studies suggest that up to 40% of obese individuals demonstrate normal insulin sensitivity (4). In addition, it is notable that the rate of increasing MBS in the population exceeds that of the rate of increasing BMI, suggesting that, while BMI may be a modulating factor, another factor independent of obesity also contributes to the development of MBS in the elderly.

It is the investigators hypothesize that the MBS in the obese elderly population is primarily linked to insulin resistance and not to obesity per se. The investigators propose to test this hypothesis by assessing MBS and insulin resistance in a population of obese elderly men and women and then determining whether or not the MBS tracks with insulin resistance.