Peter Attia MDApoB, LDL-C, Lp(a), and insulin as risk factors for cardiovascular disease [AMA 43 sneak peek]
CHAPTERS
- 0:02 – 3:21
Setting Up the AMA: Combining ApoB, Lp(a), and Insulin Questions
The host and Peter Attia banter about their shirts, then the host explains that this AMA gathers listener questions on how apoB, Lp(a), and insulin fit together in ASCVD risk. The host references earlier episodes and AMA 34 on these topics.
- •The AMA pulls together questions from past ASCVD-related content
- •Earlier episodes covered Lp(a), apoB with Alan Sniderman, and insulin with Gerald Shulman
- •Listeners wonder how the risk factors interact, such as low apoB with high Lp(a) or good insulin with raised LDL
- •Attia says he prefers talking about Formula 1 but considers apoB more important
- 3:21 – 7:11
A Race Car Analogy for ASCVD: Throttle, Brake, and the Cliff
Attia builds an analogy in which lifespan is a drive toward a cliff, with risk factors acting as throttle and brake. Lp(a) is a baseline throttle, apoB lowering is the brake, and hyperinsulinemia, smoking, and hypertension press harder on the throttle.
- •Lp(a) is a fixed baseline maintenance throttle set from birth
- •Lowering apoB to physiologic levels, mainly with pharmacotherapy, is pressing harder on the brake
- •Hyperinsulinemia presses the throttle through apoC3 expression and effects on the LDL receptor
- •Smoking, hypertension, and apoB are the big three drivers of ASCVD
- •The car can't be stopped but can be slowed to a dull roar
- 7:11 – 10:16
Starting Early: Time Horizon and Risk
The host ties the analogy to how much distance remains before the cliff and to 10-year versus 50-year risk thinking. Attia agrees that the closer you are to the cliff, the harder you need to brake, and the host stresses that younger people should care too.
- •Medicine 2.0 looks at 10-year risk while medicine 3.0 looks at 50-year risk
- •Acting earlier gives more time to adjust throttle and brake
- •Waiting longer means pressing harder on the brake
- •People in their 30s and 40s should still know their apoB and Lp(a) even with low insulin
- 10:16 – 12:49
Defining apoB Versus LDL-C
Attia clarifies what LDL-C, LDL-P, and apoB each measure. He explains that apoB is a better predictor because it counts all atherogenic particles, and that it is his main goalpost for treatment.
- •LDL-C is the cholesterol concentration within LDL particles; LDL itself is not a lab measurement
- •ApoB counts all apoB-bearing particles, including LDL, VLDL, and Lp(a)
- •Particle number drives risk more than cholesterol concentration
- •Lp(a) is generally captured inside LDL but is measured separately
- •Attia uses apoB concentration as the treatment target
- 12:49 – 14:18
Hyperinsulinemia, Type 2 Diabetes, and Higher ASCVD Risk
Attia explains that hyperinsulinemia is clearly associated with worse ASCVD outcomes, with type 2 diabetes as the extreme case. He describes the postprandial insulin response as the early canary in the coal mine and says the question is the mechanism.
- •Type 2 diabetes is an extreme manifestation of hyperinsulinemia
- •Elevated insulin after a glucose challenge can show up years before diagnosis
- •People with type 2 diabetes have roughly 50% to 2X the risk of ASCVD and all-cause mortality
- •Two mechanisms are most important: apoC-3 and endothelial dysfunction
- 14:18 – 18:26
The ApoC-3 Mechanism: Triglycerides and Rising ApoB
Attia describes how insulin resistance upregulates apoC-3, which blocks lipoprotein lipase and raises triglycerides. This leads to triglyceride-rich LDL, more particles made to carry cholesterol, and higher apoB, along with lower HDL via CETP.
- •ApoC-3 gene variants with lower expression are found in centenarians
- •Upregulated apoC-3 blocks lipoprotein lipase, reducing triglyceride use
- •Triglycerides need apoB-bearing particles like VLDL as chaperones
- •Triglyceride-rich LDL prompts the body to make more LDL, raising apoB
- •HDL cholesterol falls, likely through CETP activity, to be covered in a future HDL podcast
- 18:26 – 20:33
Insulin and Endothelial Dysfunction
Attia covers the second mechanism: insulin appears to drive endothelial dysfunction, making it easier for apoB particles to enter the subendothelial space and fuel the cascade of retention, oxidation, and foam cell formation. He notes this is harder to demonstrate than the apoC-3 mechanism.
- •Dysfunctional endothelium lets apoB particles pass more easily into the subendothelial space
- •Retained, oxidized particles are taken up by macrophages that become foam cells, driving inflammation
- •There are no great commercial assays for endothelial function
- •Cultured endothelial cells exposed to altered insulin show signaling suggesting reduced function
- 20:33 – 24:08
Assessing Your Insulin Status: The OGTT Question
The host asks how listeners can learn their insulin status beyond A1C-based diagnosis of type 2 diabetes, bringing up the OGTT as the canary-in-the-coal-mine test. The sneak peek ends before Attia answers.
- •Type 2 diabetes is defined by A1C thresholds
- •The OGTT is raised as a way to see insulin response
- •Listeners without diabetes may still wonder about their insulin level
