This answer contains spoilers… (view spoiler)[Very interesting question - not even Danny wanted to know the answer enough to subject her body to the horrors of an autopsy. Maybe he didn’t want to know that she simply stopped caring for her diabetes and that Elna was, in fact, ultimately responsible for Maeve’s death. Heart attack = not Elna’s fault, just bad genes. Diabetic coma = Elna’s fault, return to lifetime of bitterness which Danny was trying to escape. I don’t think Maeve was enough of a drama queen to act out with actual suicide, but suicide through lack of self-care / deep depression is a definite possibility. (hide spoiler)]
Julianne Kavoussi It's possible it was suicide that kills Maeve or a heart attack. She was once again hurt and devastated by her mother. Remember when Maeve slams the car brakes with her mother in the car. It's a foreshadowing of the anger and terrible emotion brewing.
Susan Grebe I don't like to think that Maeve would commit suicide. It doesn't seem in keeping with her character. She was a strong person, and didn't seem depressed. Earlier in the book, she said herself that people with Type One Diabetes have a much higher risk of developing heart problems. . And this is from the website of the National Institute of Health: "People with type 1 diabetes have a much greater risk of serious heart problems and early death. Over time, high blood glucose from diabetes can damage your blood vessels and the nerves that control your heart and blood vessels."