The trial of Claus von Bulow on charges he attempted to murder his wife, Sunny, began yesterday with the defense arguing the coma she has been in for 13 months resulted from her own overindulgence.

In opening arguments, the defense said Sunny von Bulow, who suffered from low blood-sugar levels, had abused drugs, alcohol and sweets, and that on two occasins von Bulow had even come to her aid.

"She caused her own coma and that sad fact will emerge in this trial. Claus von Bulow did not harm his wife," defense lawyer Herald Price Fahringer said.

Prosecutor Stephen R. Famiglietti painted a vastly different picture of the rich heiress the Danish aristocrat is accused of twice trying to kill with insulin injections.

"It was no accident -- not alcohol, not drugs, not carelessness on her own person" that caused her coma, Famiglietti said. "She was basically physically very healthy. She had every reason to want to live.

"It was a deliberate and malicious act of another individual -- and that other individual is the defendant," Famiglietti said.

Still another version was offered by Prince Alexander von Auersperg, 22, Sunny von Bulow's son from a previous marriage who was the prosecution's first witness. On the stand he said his mother had a penchant for sweets but added that she only "drank socially."

He told the jury that on the night of Dec. 26, 1979, his mother's voice grew weak and she staggered as he guided her to her bedroom in the mansion. A doctor was summoned the next morning because Sunny von Bulow had suffered what her son called cardiac arrest.

She was taken to Newport Hospital in a coma that the prosecution says was brought on by von Bulow's first attempt on her life. She soon recovered from that coma.

Von Auersperg said his relationship with his stepfather had been cordial until the first coma, but afterward "I became suspicious . . ."

He said he became more suspicious of Von Bulow in the year before his mother fell into her second coma but never mentioned his feelings to his mother because "I didn't feel my suspicions warranted alienating me or any other member of my family from my mother."

One month before his mother fell into the second coma, from which she is not expected to recover, von Auersperg recalled a telephone conversation with her that he said heightened his suspicions of his stepfather.

She said she wanted to get a divorce for reasons "so horrible she didn't want to tell me," von Auersperg said.

The testimony was presented before a packed courtroom and the 12 jurors charged with judging the 55-year-old defendant, who sat impassively during opening statements.

Fahringer, confiding to jurors in a near whisper, characterized Sunny von Bulow as a possessive, self-indulgent woman who made unreasonable demands on von Bulow.

"The pattern that emerges completely exculpates Claus von Bulow," Fahringer said, adding that von Bulow more than once saved his wife's life by calling an ambulance when she collapsed from her habits.

"If he wanted that woman to die, all he had to do was turn around and leave her," he said.

Famiglietti charged that von Bulow made "clandestine, subtle and ingenious attempts" to kill his wife. He said von Bulow stood to inherit half his wife's $30 million estate and "more significantly . . . was in love with another woman, a woman he remained intimate with [after the second attack]."