Browsing the medical literature, we noticed an interesting paper showing an association between high white blood cell, or leukocyte, count and the metabolic syndrome. Weird! Leukocytes live in the blood and fight infection, whereas metabolic syndrome is a cluster of related conditions having to do with diabetes and heart risk, like obesity, high blood pressure, insulin resistance, and so on. However, studies before this one have linked high leukocyte count with several of those components – high blood pressure, obesity, fat in the blood (serum triglycerides), and insulin resistance. No one really knows if a high leukocyte count causes these conditions, results from these conditions, or just occurs with them often.
Among the almost 2,000 patients in this study, 73% had metabolic syndrome, which means that they had at least two of the following: high blood pressure, central obesity (large waist circumference), high triglycerides, or low amounts of “good” cholesterol, or HDL. Most of these patients tended to be older, female (women tend to have more body fat), non-smoking (interestingly, though smoking makes people lose weight), and more likely to be on insulin for diabetes. But more interestingly, one of the findings of Dr. Tsai’s study was that patients who met more of the criteria for metabolic syndrome also tended to have higher counts of leukocytes, neutrophils, and monocytes (all types of infection-fighting white blood cells). This was true even when “adjusted for” all the other factors that can affect white blood cell counts, which means there was a true and direct correlation with metabolic syndrome.
We actually think it makes a lot of sense that amounts of these cells are elevated in patients with metabolic syndrome, because in fighting infection they activate inflammation. Recent research has suggested that chronic, low-level inflammation is an important contributor to the metabolic syndrome, type 2 diabetes, risk of heart disease, and risk of stroke. Indeed, this study showed that higher levels of these cells were associated on their own with stroke risk.
Strangely, low lymphocyte (yet another one of these white blood cells) counts were associated with higher risk of heart disease. Again, it’s not clear what exactly the causal relationship is, but some research suggests that a low lymphocyte count could be a risk factor for cardiovascular disease, since these cells help regulate plaque in the arteries.
We caution that this was only an observational study (rather than an airtight “randomized, controlled trial”), but the authors of the study suggest that white blood cells may regulate glucose, blood pressure, and lipid (fat and cholesterol) levels in the body through the release of hormones. When leukocyte counts become elevated, release of harmful levels of these hormones may contribute to the development of diabetes, high blood pressure, and a bad cholesterol profile. On the other hand, it seems that some of these hormones – some of you may have heard of leptin – actually increase white blood cell count. Whatever the mechanism and causal relationship, this may become a potential new model for looking at the link between type 2 diabetes, metabolic syndrome, and cardiovascular disease.
Source: Tsai JC-R, Sheu S-H, Chiu H-C, Chung F-M, Chang D-M, Chen M-P, Shin S-J, Lee Y-J. “Association of peripheral total and differential leukocyte counts with metabolic syndrome and risk of ischemic cardiovascular diseases in patients with type 2 diabetes mellitus.” Diabetes/Metabolism Research and Reviews. Feb 2007. 23:111-118.