Check the policy wording carefully, but generally elevated triglycerides are not considered a pre-existing condition UNLESS your doctor is treating you for it. Did your Dr. put you on Lipitor or similar statin to control your levels? If yes, you are then being treated and rules change, but if a Dr. does not consider it to be treatable, it's not a condition at all. Most policies require a condition to be stable (no change in treatment or escalation of symptoms) through an elimination period, and the elimination period can be anything from a couple of weeks to 9 months. If the elimination period is short you are fine, if it's long, you won't be covered if you are being treated.
We get our family coverage through Ingle Insurance, a Toronto based broker (but online too if not in Toronto like us), who has several options available. We have a reasonably priced package that only has a 2 week elimination period, and some other features that were important to us (like kids don't have to be with the primary policy holder to be covered - our son attends track events in the US regularly without us).