This week’s WOR program centered on the metabolic syndrome, one of the most important discoveries in the past fifty years. Until recently it was not known how several seemingly disparate illnesses occurred simultaneously, for example hypertension and heart disease. None of the facts we are about to discuss were in any of my medical school text books and were totally unknown at the time of my internal medicine residency at Maimonides Medical Center.
The metabolic syndrome is quite simply a group of three blood tests and two physical findings. It has been defined slightly differently by different health organizations in various studies. One such definition (by the IDF) is as follows:
• 1. Abdominal (central) obesity: waist circumference >37 inches (men); >31.5 inches (women) [these are lower for South Asian/Chinese/Japanese].
Plus 2 of the following 4
• 2. Blood pressure > 130/85 mm Hg
• 3. Triglycerides > 150 mg
• 4. HDL: under 40 (men); under 50 (women)
• 5. Fasting glucose > 100 mg.
Other scientific papers may utilize different measurements but the overall significance remains the same, namely that the person has an extremely high chance of developing circulatory diseases prematurely as well as the other components of the metabolic syndrome. Note that two of the criteria are essentially “pre-diabetes” and “pre-hypertension.”
What is most interesting about the metabolic syndrome is how those seemingly unrelated components are actually interconnected. There was no “central unifying thesis” until recently. The missing link was insulin resistance.
Insulin resistance, as yet only partially understood, affects all aspects of the metabolic syndrome as well as virtually all aspects of an obese body. Simply put, insulin resistance means that a person’s insulin is not functioning up to its usual capacity. It is somehow weakened or ineffective. This begins to happen in the early stages of weight gain, particularly in those individuals from diabetic families.
Ineffective insulin is unable to allow circulating glucose to enter cells of the body, most notably those in skeletal muscle and the liver. The cells which are not receiving enough energy from glucose send out messages to the pancreas, which in turn overproduces even more ineffective insulin. Thus, paradoxically, a “pre-diabetic”, will actually be producing more insulin then his or her healthy friends.
Multiple abnormalities result thereafter, all somehow related to the overproduction of ineffective insulin. One result is excessive retention of sodium by the kidneys, especially dangerous in a “civilized” country like the U.S.A with our high salt diet. Another result is circulating fats (called free fatty acids) which have numerous potentially dangerous consequences. This can most readily be seen as elevated cholesterol and triglycerides. What is unseen is a possible destructive effect of free fatty acids on the pancreas, leading to its further weakening (and diabetes).
Can we mention two of the most dreaded complications? One is a “pro-inflammatory” state, namely having highly unstable lesions in the coronary/cerebral arteries that can literally explode at any time. The other is a “pro-coagulant” state, one in which blood can clot more easily, the usual scenario for a heart attack or stroke.
The biochemistry charts depicting the various interactions we have just described are unbelievably complex. The above discussion is extremely simplified, and a great deal is not known as yet. However we are dealing with an illness, obesity, that clearly has warning signs well in advance of potential disaster. If you have the metabolic syndrome, you have already developed insulin resistance. And if you have insulin resistance you may already have done serious damage to your heart, brain, and kidneys. The need to take weight off and keep it off would therefore be the most important item on your “to do” list.
Here’s a little more information for those who want bonus points and wish to demonstrate amazing scientific knowledge to their friends:
Metabolic abnormalities associated with insulin resistance
• Endothelial dysfunction (increased adhesion molecules, increased cellular proliferation, less vasodilatation)
• Dyslipidemia (increased free fatty acids, TG, small dense LDL; decreased HDL, adiponectin)
• Procoagulant state (increased PAI-1, fibrinogen)
• Inflammation (increased CRP, IL-6)
-European Journal of Pharmacology 2004
------------------------------------------------------------------------------------------------
• 1/3 of the USA population is insulin sensitive.
• 1/3 of the population is insulin resistant. These people have very high insulin levels and really need intervention.
• 1/3 is in the middle.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment