PracticeUpdate Diabetes June 2019

EXPERT OPINION 14

Obesity and Cardiovascular Disease in Teenagers Interview with Peter Libby MD by Aman Shah MD

Dr. Shah: I wanted to talk to you about obesity and car- diovascular disease, especially in the teenage and the younger adult population. Is there a link between these two things in teenagers? Dr. Libby: Right. Well, obesity in and of itself may not be a causal risk factor, but it’s certainly a marker for dysmetabolism, which we think, over the years, can contribute to the burden of cardiovascular risk. And thank you for asking about the vulnerable adoles- cent population because although we’ve made great inroads in cardiovascular prevention, there are sec- ular trends towards decrease in cholesterol, towards a decrease in blood pressure, smoking cessation has grown more widespread, particularly in the US. So we’re making progress there, but I am afraid that we’re sitting on a time bomb because of the epi- demic of childhood obesity going hand in hand with the risk of type 2 diabetes, which we know is an established cardiovascular risk factor. So I think we need to be very mindful that some of the progress that we’ve been able to make over the last decades in combating cardiovascular dis- ease may hit a roadblock as the current generation of overweight or obese kids grows to maturity and enters the period of vulnerability for ischemic heart disease and other complications. Dr. Shah: Have we quantified that risk in terms of how obese a teenager is and how much that might increase her risk of cardiovascular diseases? Dr. Libby: There is, in general, a relationship between the degree of obesity and the degree of dysmetabolism. In particular, we’re concerned about the ectopic fat or visceral fat. So as you know, there’s a difference in the way in which fat can be distributed. And since the pioneering work of Jean Vague in the 1940s and Per Björntorp, we’ve known that people who develop subcutaneous depots of fat…this is often the gynoid distribution, more

common in women, that that is less metabolically costly than the visceral obesity, which tends to be the problem with men, which is not subcutaneous but actually, say, in the omentum and surrounding the viscera. And also we’re concerned these days, and it’s a hot topic in cardiovascular research now, on ectopic fat, particularly perivascular fat, perivascular adipose tis- sue, and pericardial fat. So it’s these ectopic deposits of fat that seem to be teeming with inflammatory cells and can pour out inflammatory mediators that we know can trigger glucose intolerance and insu- lin resistance, and so we have a vicious circle going here. So it’s that belly fat that we men are particu- larly prone to. And I don’t need to remind you that South Asians and Asian populations can develop this metabolism with much lesser deposits of vis- ceral fat than many Caucasians. So the International Diabetes Federation actually has different criteria for waist circumference for South Asians and Asians than for Caucasians perhaps because of that thrifty gene hypothesis – to survive starvation, you had to be able to lay down fat. That gets turned against us when we move from the millennia of striving for sufficient nutrition to over-abundance of food and over-nutrition. Dr. Shah: Let’s look at the quantification from the other perspective. From what I understand, we have really good data, which says that if you reduce body weight by even a modest amount like 5% or 10%, you reduce diabetic risk. Is there similar data for reducing cardio- vascular risk and weight loss? Dr. Libby: I wish there were, but perhaps the best data- base for this, the most informative study is the Look AHEAD trial, which was a fantastic investment of

" …my approach is to make Pascal’s Wager about lifestyle intervention for cardiovascular prevention. I don’t think that we’re ever going to have the data, so I’m going to place Pascal’s Wager in favor of its working, thinking that if I behave in a healthy way, that I will improve my cardiovascular outcomes. "

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