High Cholesterol and Blood Sugar: The Impact of Diet on Blood Glucose and Lipid Levels in Diabetes

High Cholesterol and Blood Sugar: Diabetes as a Risk Factor for Disease

Type 2 diabetes is one of the major risk factors for cardiovascular diseases. If left unmanaged, it can lead to stroke or heart attack. That’s why maintaining a healthy lifestyle and undergoing regular checkups is so important.

Abnormal blood test parameters, such as high cholesterol, can accelerate the onset of diabetes complications. However, lifestyle changes can delay or even prevent these adverse outcomes.

Type 2 Diabetes and Its Impact on Health

To understand how diabetes affects cholesterol levels and contributes to other conditions, it’s helpful to understand the mechanism behind its development.

How Does Type 2 Diabetes Develop?

Type 2 diabetes is most commonly associated with excess body weight. An excessive amount of body fat leads to increased inflammation in the body and the development of insulin resistance.

Insulin resistance means that the body’s tissues become less sensitive to insulin—a hormone produced by the pancreas that lowers blood glucose after eating. This means the body’s cells are no longer able to efficiently use the glucose circulating in the blood in response to insulin.

Beta cells in the pancreas initially compensate by producing more insulin to maintain normal blood glucose levels. But chronically high insulin levels (hyperinsulinemia) worsen insulin resistance over time.

At this stage, pancreatic cells become hypertrophied. Eventually, they begin to die off, leading to decreased insulin production. As a result, persistently elevated blood glucose levels emerge.

How to Check If You Have Diabetes?

If you suspect carbohydrate metabolism issues or insulin resistance, test your fasting blood glucose and insulin levels.

A complete picture of your carbohydrate tolerance is provided by the oral glucose tolerance test (OGTT). This test starts with a fasting blood draw. Then, you drink a solution containing 75 grams of glucose.

Further blood samples are collected at 1 and 2 hours after consuming the glucose solution. Glucose and insulin levels are measured to assess how your body handles carbohydrates. This test requires a referral from your doctor.

High Cholesterol and Blood Sugar: The Effect of Diabetes on Lipid Levels

Diabetes is usually associated only with carbohydrate metabolism disorders. However, it also increases the risk of cardiovascular disease by 2 to 4 times due to its negative impact on lipid parameters (1).

Diabetic Dyslipidemia

Diabetic dyslipidemia refers to both qualitative and quantitative abnormalities in cholesterol fractions. It is usually characterized by reduced levels of “good” HDL cholesterol and elevated levels of triglycerides (TG) and LDL (“bad” cholesterol).

This is due to inadequate insulin secretion, high glucose levels, and accompanying insulin resistance. These factors increase lipolysis and inhibit lipogenesis. As a result, serum triglyceride and free fatty acid levels rise.

LDL particles become structurally altered, making them more atherogenic. This modified LDL more easily embeds into arterial walls, contributing to plaque formation.

Additionally, the chronic inflammation associated with diabetes impairs endothelial function. It facilitates the adhesion of altered cholesterol particles to blood vessel walls and contributes to elevated blood pressure.

Elevated Glucose and Cholesterol: What Tests Should a Person With Diabetes Have?

Every person diagnosed with type 2 diabetes should test their individual cholesterol fractions.

What Should Cholesterol Levels Be in Diabetes?

Due to the increased cardiovascular risk in this population, reference values are lower (2). Recommended LDL-C cholesterol levels in diabetes are:

• For those at very high cardiovascular risk: <55 mg/dL (<1.4 mmol/L) or at least a 50% reduction.

• For those at high cardiovascular risk: <70 mg/dL (1.8 mmol/L) or at least a 50% reduction.

• For moderate cardiovascular risk, under age 50, with diabetes for less than 10 years and no other risk factors: <100 mg/dL (2.6 mmol/L).

HDL-C has no set target, but levels >1.0 mmol/L (>40 mg/dL) in men and >1.2 mmol/L (>45 mg/dL) in women are associated with the lowest cardiovascular risk.

Triglycerides also have no official target, but levels <1.7 mmol/L (<150 mg/dL) are linked with the lowest risk.

A Balanced Diabetic Diet and Its Effect on the Lipid Profile

In addition to regulating blood glucose, a diabetic diet directly affects blood lipid levels. Key dietary components include:

Dietary Fiber

Mainly found in whole grains, vegetables, fruits, and legumes. In the gut, fiber binds cholesterol and bile acids, increasing their excretion. It also nourishes gut microbiota, which plays a role in fat metabolism.

Mono- and Polyunsaturated Fatty Acids

These occur primarily in plant oils, fish, nuts, and seeds. They increase HDL cholesterol and decrease LDL cholesterol. They also have anti-atherosclerotic effects by reducing inflammation and inhibiting blood clotting.

Reducing Saturated and Trans Fats

Avoiding animal fats, red meat, and highly processed foods improves lipid profiles and reduces the risk of coronary heart disease.

B Vitamins

Folic acid, B6, and B12 participate in homocysteine metabolism. Homocysteine is formed from the sulfur-containing amino acid methionine. High homocysteine levels contribute to endothelial dysfunction, increased LDL levels, and increased blood clotting. Adequate intake of these vitamins helps maintain homocysteine balance.

Antioxidants

These compounds neutralize free radicals and reduce their formation. They also reduce the atherogenicity of LDL particles and protect the vascular endothelium, preventing atherosclerotic changes. Antioxidants also have anti-inflammatory and anti-cancer effects.

Dietary intervention and weight reduction help improve blood biochemical parameters. Studies show that a 10% weight loss significantly:

• lowers triglycerides (TG),

• lowers LDL cholesterol,

• lowers total cholesterol,

• raises HDL cholesterol,

• lowers blood glucose (3).

The Effect of an Improper Diet on Lipid Parameters

It’s important to emphasize how a poorly balanced diet impacts lipid levels. Animal products are high in cholesterol, saturated fats, and trans fats—all of which raise LDL cholesterol.

They also increase the risk of plaque formation, promote blood clotting, and contribute to cancer and neurodegenerative diseases.

Trans fats occur naturally in meat but can also be found in processed foods due to industrial processes. Manufacturers add them to sweets like wafers, biscuits, pretzels, crackers, and cookies.

Sweet snacks also contain sugar in various forms (e.g., sucrose, glucose-fructose syrup, inverted sugar, or barley malt).

Monitoring Cholesterol and Glucose in Diabetes: Summary

Diabetes disrupts lipid metabolism, leading to increased levels of “bad” LDL cholesterol. Abnormal lipid parameters promote serious cardiovascular diseases.

The primary goal of treating type 2 diabetes is to maintain optimal blood glucose levels. In addition to monitoring glycemia, it is also essential to monitor the lipid profile.

Disturbances in other biochemical markers are usually the result of excess body weight, lack of physical activity, and chronic hyperglycemia. All of these factors are influenced by your diet. Therefore, proper nutrition is essential for keeping these parameters within normal ranges.