Triglycerides and HDL: what they say about your metabolic health

LDL cholesterol gets most of the attention in a lipid test, but the other two numbers, triglycerides and HDL, often say more about how your body is handling food and energy. When triglycerides are high and HDL is low, it usually reflects a metabolism under strain, well before blood sugar starts to rise.

What triglycerides are

Triglycerides are the main form of fat in your blood and in your body's fat stores. Some come directly from the food you eat. Others are made by your liver, particularly from excess sugar, refined starch and alcohol. After a meal, triglycerides rise for several hours, which is why they are best measured fasting.

The triglyceride ranges

LifePrint uses a fasting limit below 1.7 mmol/L, in line with the SA Heart and LASSA 2018 guideline and the ESC/EAS 2019 guideline. Higher results are graded:

• 1.7 to 2.3 mmol/L: borderline, shown in LifePrint's grey zone.
• Above 2.3 mmol/L: high.
• 5.6 mmol/L and above: very high.
• 10 mmol/L and above: marked as urgent, because levels this high carry a risk of pancreatitis, a painful and potentially serious inflammation of the pancreas.

What HDL is

HDL, high density lipoprotein, carries cholesterol away from tissues and back to the liver. It is often called “good” cholesterol, because people with low HDL tend to have more heart disease. LifePrint uses the SA Heart and LASSA 2018 and ESC/EAS 2019 markers of risk: HDL above 1.0 mmol/L in men and above 1.2 mmol/L in women.

HDL is more complicated than its nickname suggests. Medicines that raise HDL have not reduced heart attacks in trials, and very high HDL levels do not seem to give extra protection. So low HDL is best seen as a marker of an unhealthy metabolic pattern, rather than a number to push up for its own sake.

Why the two travel together

When cells become less responsive to insulin, the liver makes more triglyceride rich particles. As these circulate, they swap contents with HDL and LDL particles. HDL ends up smaller and is cleared faster, so its level falls. LDL particles become smaller and more numerous, which is why ApoB can be high even when LDL cholesterol looks acceptable.

This pattern of high triglycerides, low HDL and many small particles is common in people with weight around the middle, prediabetes, type 2 diabetes, fatty liver, high blood pressure and polycystic ovary syndrome. It often appears years before blood sugar crosses into the diabetes range.

Reading them with the rest of the panel

The Heart and Metabolic panel is built to catch this pattern. Alongside the lipids, it includes:

• Fasting glucose and HbA1c, to see where your blood sugar stands against the SEMDSA criteria.
• Fasting insulin, a supporting marker of insulin resistance. No guideline sets a cut-off for it, so it is read with the lab's range and your other results.
• ALT and GGT, which often rise with fatty liver.
• Uric acid, which tends to rise with insulin resistance.
• ApoB and hs-CRP, which help show how much the pattern is adding to heart risk.

Other causes of high triglycerides

Not every high triglyceride result is about insulin resistance. Regular alcohol, an underactive thyroid, reduced kidney function, some medicines, including steroids, some HIV treatments and certain psychiatric medicines, and pregnancy can all raise triglycerides. Some people inherit a tendency to very high levels. Your doctor will consider these if your result is well above the range.

What moves triglycerides and HDL

Triglycerides respond to lifestyle change faster and more dramatically than almost any other blood marker. HDL moves more slowly, but tends to follow. The changes with the best evidence are:

• Cutting back on sugar, sweetened drinks, fruit juice and refined starch such as white bread and white rice.
• Reducing alcohol, which has a strong effect on triglycerides in many people.
• Losing excess weight, particularly from around the middle.
• Regular aerobic activity and strength training.
• Stopping smoking, which helps raise HDL.
• Eating oily fish, such as sardines, pilchards, mackerel or salmon, a couple of times a week.

When triglycerides remain very high despite these changes, or when overall heart risk is high, your doctor may recommend medicine. Do not start fish oil or other supplements for this purpose without speaking to your doctor first.

The takeaway

High triglycerides and low HDL are not just numbers on a lipid report. They are an early, reversible signal about your metabolic health. If yours are outside the range, discuss them with a registered healthcare practitioner, and consider a repeat after about three months of change to see the difference. Your LifePrint report is health information, not a diagnosis.