Epidemiology

Diabetes ups risk for liver disease

NEW YORK (Reuters Health) - Newly diagnosed type 2 diabetes raises the long-term risk of cirrhosis, liver failure and liver transplantation, according to a population-based study in Canada.

In nearly half a million diabetics and more than 2 million control subjects, the incidence of these outcomes was low - but the difference between diabetics and controls was statistically significant.

During a median follow-up of 6.4 years, the incidence rates for serious liver disease (cirrhosis, liver failure, or transplantation) per 10,000 person-years were 8.91 for patients newly diagnosed with diabetes, versus 4.17 in the general population. After accounting for age, income, urban residence, recent hospital admissions and pre-existing hypertension, dyslipidemia, obesity, and cardiovascular disease, the adjusted hazard ratio was 1.77.

The risk was highest for cirrhosis (aHR 2.55), followed by liver failure and its sequelae (aHR 1.69) and liver transplantation (aHR 1.31), the researchers report in the June 21st online issue of the Canadian Medical Association Journal.

One potential mechanism, co-author Dr. Joel G. Ray told Reuters Health, is that "the state of insulin resistance that predisposes someone to type 2 diabetes causes persistent fatty liver," leading to inflammation and ultimately to cell destruction. Another possibility is that high glucose levels directly injure the liver.

Dr. Ray, from the University of Toronto, and associates searched health claims from the Ontario Health Insurance Plan to identify 438,069 adults aged 30 to 75 diagnosed with diabetes between 1994 and 2006, and 2,059,708 controls matched by age, sex, and geographic region. They excluded people diagnosed with liver disease or an alcohol-related condition in the 3 years before the index date.

When a diabetic patient presents with elevated liver enzymes, "the first sensible thing is to make sure it's not caused by medication, because that's reversible and critical to think of for certain drugs," Dr. Ray said. The next step would be to rule out viral hepatitis.

After that, it's safe to assume that diabetic hepatopathy is involved, for which Dr. Ray recommends "reducing liver fat through weight reduction and lipid control."

But he does not advocate annual screening for liver disease until research establishes that interventions will benefit the patient. "Otherwise," he said, "if doctors sees the ALT go up, they may push someone to have a liver biopsy that they don't need, or prescribe a drug that's not been proven effective."

http://www.cmaj.ca/cgi/content/abstract/cmaj.092144v1

CMAJ 2010.

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