Cholesterol and Diabetes

For people with diabetes, keeping your cholesterol under control is important—we've got to work hard to prevent long-term cardiovascular complications of diabetes.  While tight blood glucose control is a crucial part of that, watching your cholesterol numbers can also help prevent cardiovascular disease.

Even though the average American has lowered his or her cholesterol, the average still remains in the borderline range—slightly over 200 mg/dl. Although people are eating less fat than in years past, we as a culture are becoming more obese. Those who are asked to take cholesterol lowering medications often stop for various reasons. For one thing, there may be few symptoms, and many people are more afraid of cancer so they don't take this seriously, and because this is a chronic disease many people get bored or decide they have better ways to spend their funds than on expensive medications.

Cholesterol Numbers for People with Diabetes

It's important to know your cholesterol numbers.

If you're healthy, your numbers should be:

  • total cholesterol: below 200 mg/dl
  • total triglycerides: below 200 mg/dl
  • HDL cholesterol (the "good" cholesterol): above 45 mg/dl
  • LDL cholesterol (the "bad" cholesterol): below 130 mg/dl

If you have coronary artery disease:

  • total cholesterol: below 200 mg/dl
  • total triglycerides: below 200 mg/dl
  • HDL cholesterol: above 35 mg/dl
  • LDL cholesterol: below 100 mg/dl

Current Cholesterol Research

Current genetic research has found the gene (called ABC) that controls HDL cholesterol. Hopefully, in the next years, a medication will be found that will boost protein that removes cholesterol from artery walls leading to transport out of the body by HDL.

Other research has found a gene called MTP which seems to cut production of LDL cholesterol.

Still other research shows that 10% of high cholesterol cases are related to thyroid function or hypothyroidism. One of the observed side effects of hypothyroidism is an elevation in LDL cholesterol. Elevated LDL has been associated with coronary artery disease and peripheral vascular disease.

In the most severe cases of hypothyroidism, the disease causes a marked elevation in triglyceride levels.

Recent studies point to the need that all patients with hypercholesterolemia should have tests of their thyroid function since a small percentage of these persons will have hypothyroidism contributing to their cholesterol problem.

Treatment with thyroid hormone will lower cholesterol levels in those patients with an abnormal cholesterol from hypothyroidism. Long-standing, untreated hypothyroidism can lead to permanent damage to the coronary arteries and other blood vessels. Therefore, it is important to treat hypothyroidism and monitor cholesterol levels closely.

High Cholesterol Risk Factors

There are significant risk factors for developing high cholesterol. These are mostly controllable:

  • inactivity: Lack of exercise may lower your levels of good cholesterol HDL.
  • obesity: Excess weight increases your level of triglycerides and can lower HDL. It can also increase your level of very-low-density lipoprotein cholesterol.
  • diet: Eating a high-fat, high cholesterol diet contributes to an increase in blood cholesterol level. Even polyunsaturated fats are susceptible to oxidation and over time speeds buildup of plaque inside arteries.

Other factors that increase your likelihood of high cholesterol:

  • smoking: This damages the walls of your blood vessels, making them prone to the accumulation of deposits. It also lowers levels of HDL as much as 15%.
  • high blood pressure: This damages the walls of your arteries so that it becomes easier to accumulate fatty deposits.
  • type 2 diabetes: Chronic high blood glucose levels leads to narrowing of arteries.
  • family history of atherosclerosis: If a close relative (parent or sibling) has developed atherosclerosis before age 45, high cholesterol levels place you at a greater risk than average for developing atherosclerosis.

Dyslipidemia in Adults with Diabetes:  ADA Position Paper

In 2004, the American Diabetes Association released a position paper on management of dyslipidemia in adults with diabetes.1  It said that dyslipemia management is especially important for those with type 2 diabetes, because type 2 is associated with a two to fourfold excess risk of coronary heart disease (CHD).

The relationship between uncontrolled diabetes to macrovascular disease is not completely understood. The reason for this is that researchers have found an increased risk for cardiovascular disease before the diagnosis of type 2 diabetes.

Clearly this points to a need for aggressive screening for diabetes combined with improved glycemic control.

The most common pattern of dyslipidemia in type 2 diabetics is elevated triglyceride levels and decreased HDL cholesterol levels. Type 2 diabetics typically have a preponderance of smaller, denser LDL particles, which possibly increases atherogenicity even if the absolute concentration of LDL cholesterol is not significantly increased. It is also known that the mean triglyceride level in type 2 diabetes is <200mg/dl, and 85% to 95% of patients have triglyceride levels below 400 mg/dl.

In terms of research for understanding the amount of lipids and lipoproteins as predictors of CHD in type 2 diabetes, the results are scarce. No trials on the effects of lipid-lowering agents on subsequent CHD in diabetic patients has been done so far.

However, some studies did include a small number of those with type 2 diabetes and in all, medication had a positive effect on CHD. What is known is that all glucose lowering agents lower triglyceride levels; however, they have only a modest effect on raising HDL.

LDL cholesterol may decrease modestly (up to 10% to 15%) with the achievement of glycemic control. Since improved glycemic control may also lower triglyceride levels, it might also cause a favorable change in LDL composition.

In people with diabetes, optimal blood levels are:

  • LDL cholesterol levels: <100 mg/dl
  • HDL cholesterol levels:  >45 mg/dl
  • triglyceride levels:  <200 mg/dl

Because of the frequent changes in glycemic control in diabetic patients and their effects on levels of lipoprotein, levels of LDL, HDL, total cholesterol, and triglyceride should be measured yearly in adult type 2 diabetes patients. If values fall below in lower-risk levels, assessment may be repeated every 2 years

In children with diabetes, consideration should be given to measuring lipoproteins after age 2.

High Cholesterol Treatment When You Have Diabetes

The recommendations for treatment of elevated LDL cholesterol generally follows guidelines of the National Cholesterol Education Program and the American Diabetes Association with the following caveats: Pharmacological therapy should be initiated after behavioral interventions are used. However, in patients with clinical coronary vascular disease (CVD) or very high LDL (>200 mg/dl), pharmacological therapy should be initiated at the same time behavioral therapy is started.

Treatment of LDL cholesterol is considered first priority for pharmacological therapy of dyslipidemia for a number of reasons. The initial therapy is behavioral with weight loss, increased physical activity, and moderation of alcohol consumption.

In severe hypertriglyceridemia (>1,000mg/dl), severe dietary fat restriction (<10% of calories) in addition to pharmacological therapy is necessary to reduce the risk of pancreatitis.

After the achievement of optimal glycemic control, the physician may consider adding a fibric acid. Above 400 mg/dl triglyceride levels pharmacological treatment is warranted.

In some studies, high doses of statin therapy were moderately effective in reducing triglyceride levels in markedly hypertriglyceridemia subjects (triglyceride >300 mg/dl).

Ask your physician about classes of medications which include resins (Questran and Colestid), triglyceride-lowering drugs (Lopid, Tricor and Niacin), and Statins (Lescol, Mevacor, Zocor, Pravachol, Lipitor and Baycol).

Type 1 diabetic patients who are in good control tend to have normal levels of lipoprotein. Their composition of lipoproteins may be abnormal, but the effects of this on CHD is unknown.

It does, however, seem reasonable that if type 1 diabetic patients have high LDL levels that they should meet the same goals as those for type 2 diabetic patients. The position paper suggests that improved glycemic control may be more important in type 1 diabetic patients than type 2 in the reduction of CHD.

The paper concludes that aggressive treatment of diabetic dyslipidemia will probably reduce the risk of CHD in persons with diabetes. Primary therapy should be directed to reduce LDL levels. The initial therapy for hypertriglyceridemia is to improve glycemic control.

Cholesterol and Diabetes Conclusion

The moral of all of these facts is to know your numbers and talk to your doctor to make sure you are within the guidelines for your own good health. Do talk over how to manage your diet and discuss "good" fats, fish oils, complex carbohydrates, photochemical packed foods, black tea, red wine, soy products and any other foods that you read about.

Perhaps they will fit into your diet and be of help; perhaps they won't. Don't start on your own as they all have calories, and you don't need those extra calories when you have diabetes. Something may have to be taken away from your meals to incorporate these new foods as you work to control your cholesterol.

Updated on: March 11, 2013