Research has shown that obesity, hypertension, and diabetes tend to be linked, and obesity and diabetes are rising on an epidemic scale (1). Therefore, it is important to understand the effects of having these three illnesses on health and quality of life. One study looked at the relationship between having these diseases and the health-related quality of life (HRQL) for people 60 and above. The study showed that individuals who were solely obese, solely hypertensive, or solely diabetic registered a worse HRQL on all the scales more frequently than those without the three risk factors (1). In men, diabetes was the single factor to be significantly associated with the greatest reduction in HRQL on most scales, while for women, it was obesity. Women who had all three diseases showed the maximum decline in HRQL across all of the scales, and the decline is greater than can be expected from the individual scores for the three factors combined (1). This shows that for this type of health rating scale, the negative effects of obesity, hypertension, and diabetes on individuals’ health are greater than the effects of the three combined.
Each of the risk factors (obesity, hypertension, and diabetes) can also interfere with each other and effect the treatment of these diseases. One example is the effects of obesity and hypertension on the treatment of diabetes. Resistance to insulin-mediated glucose disposal has been previously shown to be increased in association with obesity and high blood pressure (2). In a recent study, non-obese subjects with normal blood pressure had values that were significantly lower from the other groups tested (obese-normal blood pressure, non-obese-high blood pressure, obese-high blood pressure, and high blood pressure-obese-noninsulin-dependent diabetes mellitus) for plasma glucose and insulin responses and steady-state plasma glucose concentrations (2). Respective to their weight-matched controls, subjects with high blood pressure, regardless of weight, had significantly higher plasma glucose responses and steady-state plasma glucose concentrations. The highest plasma glucose responses and steady-state plasma glucose concentrations were in obese subjects with both high blood pressure and non-insulin-dependent diabetes mellitus(2). The results of this study support the idea that the negative effects of obesity, hypertension and diabetes are additive, and having multiple risk factors can lead to complications in the treatment of each of the illnesses.
Another recent study of 2,475 subjects found that 83.4% of the hypertensives were either glucose intolerant or obese, and both established insulin-resistant conditions (3). For these subjects the mean increment in summed insulin levels (milliunits per liter) compared with non-obese normotensives with normal tolerance was 12 for hypertension alone, 47 for obesity alone, 52 for abnormal tolerance alone, and 124 when all three conditions were present. Researchers found that insulin resistance/hyperinsulinemia are present in the majority of hypertensives, and they constitute a common pathophysiologic feature of obesity, glucose intolerance, and hypertension, providing a possible explanation for their ubiquitous association (3).
When looking at the effects of being overweight and having diabetes on developing other illnesses such as coronary heart disease and stroke, researchers looked at four different groups of people and compared the combinations to see if there is an additive effect of obesity and diabetes for developing the other illnesses. According to this study, CHD was more frequent among diabetic subjects, and even more frequent among overweight diabetic subjects. Stroke, on the other hand, was more among diabetic subjects, but was as frequent in overweight and lean diabetic people (4). This study suggests that obesity and diabetes are additional risk factors for CHD, but not for stroke.