Islamabad - Previous studies have suggested that lack of sleep may increase the risk for cardiovascular disease and a new study may help explain why researchers found that sleep deprivation may have a negative impact on cholesterol levels.

Lack of sleep may have a big impact on cholesterol, a new study suggests. The study found that sleep loss leads to changes in genes that are responsible for regulating cholesterol levels.

What is more, two population cohorts reveal that people who experience sleep deprivation may have fewer high-density lipoproteins (HDL) - known as the “good” cholesterol - than those who have sufficient sleep.

HDL cholesterol is responsible for removing low-density lipoproteins (LDL) - the “bad” cholesterol - from the arteries.

LDL cholesterol contributes to atherosclerosis - a build-up of plaque in the arteries that can increase the risk for heart attack and stroke - so a robust HDL cholesterol level is important for protecting heart health.

The team reached its findings by conducting experimental and epidemiological analyses. For the experimental analysis, the researchers enrolled 21 participants who were required to sleep in a laboratory-controlled condition for 5 nights

The sleep duration for 14 of these participants was restricted to just 4 hours a night, while the remaining seven participants enjoyed sufficient sleep each night.

Blood samples were taken from all subjects during the study period, which the team analyzed for gene expression and lipoprotein levels.

Compared with participants who had sufficient sleep, the researchers found that those who experienced sleep loss had reduced expression for genes that encode for lipoproteins - that is, there was reduced activity in genes that are responsible for regulating cholesterol levels.

For the epidemiological analysis, the researchers assessed the data of 2,739 participants from one of two Finnish population studies: Dietary, Lifestyle and Genetic determinants of Obesity and Metabolic syndrome (DILGOM) study, and the Cardiovascular Risk in Young Finns Study (YFS).

In the DILGOM study, participants completed questionnaires in which they were asked whether they got enough sleep each night. Subjects who answered “seldom” or “never” were deemed as having “subjective sleep insufficiency.”

In the YFS study, subjects were asked how many hours they slept each night and how many hours they need each night to fell well-rested. Their subjective sleep duration was then subtracted from their subjective sleep need in order to determine which participants could be deemed as having sleep deprivation.

On analyzing the blood samples of the participants, once again, the researchers found that subjects who were not getting sufficient sleep had reduced expression of lipoprotein-encoding genes, compared with those who were getting enough sleep.

Common diabetes drug may raise risk of developing cancer

A common diabetes drug may raise the risk of developing bladder cancer, a study of British patients has found. The anti-diabetic drug pioglitazone helps to control blood sugar levels in patients with type 2 diabetes.
But new research has found that taking the drug is linked to a 63 per cent increased risk of bladder cancer. Figures from the Health and Social Care Information Centre show 1.18 million prescriptions for pioglitazone hydrochloride were dispensed in England in 2014.

“The results of this large population based study indicate that pioglitazone is associated with an increased risk of bladder cancer,” said lead author Dr Laurent Azoulay, Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Montreal, Quebec, Canada.

Researchers wanted to assess the drug after a number of bladder cancer cases were identified among people taking the drug in a trial in 2005. Since then different studies have reported contradictory findings on the subject.

They set out to compare pioglitazone to other anti-diabetic drugs.

Experts identified 145,806 patients from the UK Clinical Practice Research Database newly treated with anti-diabetic drugs between January 2000 - when pioglitazone and another medicine from the same class of drug called rosiglitazone first entered the UK market - and July 2013, with follow-up until July 2014.

Overall, 622 of these patients received a diagnosis of bladder cancer during the follow-up period.

Anti-diabetes drugs help control blood sugar but diabetics must still inject insulin Credit: Alamy
The team of Canadian-based researchers found that compared to other anti-diabetic drugs, pioglitazone was associated with an increased risk of bladder cancer. The risk heightened with increasing duration of use and dose, they found.

No increased risk was found for rosiglitazone - the drug was withdrawn from use in 2010 due to an increased risk of cardiovascular disorders, including heart attack and heart failure.

Type 2 diabetes affects 3.3 million people in England and Wales and there is currently no cure. It can lead to blindness, stroke, kidney failure and limb amputation.

Around 10,000 people are diagnosed with bladder cancer each year and more than 5,000 die from the disease.
The researchers said that patients should be informed of the risk so that they could choose whether to remain on the drug.

In an accompanying editorial, Victor Montori, Professor of Medicine at Mayo Clinic in the US suggested that working closely with their clinicians, “patients can identify the agent that is best for them given their context, both clinical and personal.”

A separate study by Nottingham University, also reported in the BM, found that risk of kidney disease and blindness was raised depending on which combination of anti-diabetes drugs a patient took. Taking metformin alone significantly lowered the risk of severe kidney disease.

The scientists say the results may have implications for prescribing, and suggest doctors and patients should be aware when assessing the overall risks and benefits of diabetes drugs.