A recent study published within the journal Scientific Reports assessed the associations between the change in total cholesterol (TC) levels after type 2 diabetes (T2D) diagnosis (relative to pre-diagnosis levels) and the chance of heart problems (CVD).

CVD is the worldwide leading reason for mortality. T2D is a gateway disease to CVD. A study revealed higher coronary heart disease (CHD) and stroke risks in diabetes patients than in non-diabetic individuals. The worldwide prevalence of T2D is anticipated to exceed 10% by 2030. Subsequently, stopping CVD in individuals with diabetes might be of public health significance.

Hypercholesterolemia is a big risk factor for CVD, and its hostile effects on CVD might be more evident in individuals with metabolic conditions, e.g., T2D. Diabetes patients could also be more vulnerable to hypercholesterolemia’s negative impact on CVD risk. Nonetheless, T2D diagnosis often ends in positive lifestyle changes helping reduce hypercholesterolemia or CVD risk.

Study: Changes in total cholesterol level and heart problems risk amongst type 2 diabetes patients. Image Credit: crystal light / Shutterstock

In regards to the study

In the current study, researchers explored the connection between the change in TC levels pre- and post-T2D diagnosis with the chance of CVD. They chose participants with T2D from 2003 to 2012 from the National Health Insurance Service – Health Screening cohort in Korea. Patients were identified using relevant International Classification of Diseases, Tenth Revision (ICD-10) codes and based on the prescription history of anti-diabetes drugs.

Circulating TC levels were estimated after an eight-hour fasting period. TC levels two years before and after T2D diagnosis were classified into low (< 180 mg/dL), middle (180 to 239 mg/dL), and high (≥ 240 mg/dL). Accordingly, participants were stratified into high-low, high-middle, high-high, middle-low, middle-middle, middle-high, low-low, low-middle, and low-high groups based on the change in TC levels after T2D diagnosis from pre-diagnosis levels.

The first consequence was the incidence of non-fatal CVD. The secondary consequence was the incidence of stroke or CHD. The team computed the cumulative probability of the incidence of CVD in accordance with changes in TC levels. Hazard ratios of outcomes were calculated using Cox proportional hazards model. Moreover, the team performed a sub-group evaluation in accordance with using lipid-lowering drugs. Sensitivity analyses were restricted to those using statins.

Findings

The study included 23,821 participants; 9.9% were diagnosed with CVD. The incidence of CHD and stroke was 4.9% and 5.1%, respectively. Patients with increased TC levels after T2D diagnosis were more likely to have higher use of lipid-lowering drugs, body mass index (BMI), fasting serum glucose, blood pressure, aspartate transaminase, alanine transaminase, and lower physical activity in comparison with those that had constant or unchanged TC levels post-T2D diagnosis.

Most participants taking lipid-lowering drugs used statins. The cumulative probability of the incidence of non-fatal CVD amongst T2D patients was significantly elevated within the low-middle, low-high, and middle-high groups. Conversely, it was significantly lower in middle-low, high-middle, and high-low groups. Higher and lower TC levels post-T2D diagnosis were related to elevated and reduced CVD risk, respectively.

The chance of CVD increased within the low-middle and low-high groups but decreased within the high-middle group amongst participants not using lipid-lowering drugs. Amongst patients who used these drugs, the chance of CVD was higher within the low-middle group but lower within the high-middle and high-low groups. There was no evidence of interactions between using lipid-lowering drugs and the change in TC levels within the sub-group evaluation.

The association of the change in TC levels was consistent for the chance of CHD or stroke but differed by means of lipid-lowering drugs within the sub-group evaluation. Nonetheless, the outcomes weren’t different in sensitivity analyses restricted to statin users. Moreover, the researchers conducted analyses in participants with data on high-density (HDL-C) or low-density lipoprotein cholesterol (LDL-C) and triglycerides.

There was no association between CVD risk and the changes within the triglyceride and HDL-C levels pre- and post-T2D diagnosis. Nonetheless, a ten mg/dL increase in LDL-C levels after T2D diagnosis relative to pre-diagnosis levels was related to a better risk of CVD and CHD, especially amongst those using lipid-lowering drugs.

Conclusions

Taken together, increased TC levels in T2D patients relative to pre-diagnosis levels were related to a better risk of CVD, whereas reduced TC levels were related to a lower CVD risk, no matter using lipid-lowering drugs. Results were consistent for the chance of stroke and CHD. Females were likelier to exhibit no improvements in TC levels despite using lipid-lowering drugs. Subsequently, the findings suggest that managing TC levels in T2D patients is likely to be clinically significant in mitigating the chance of CVD.