As a follow-on to the previous post, I thought I'd just come back to the point about cardiac failure also predisposing to hypoglycaemia.
It isn't immediately clear why this should be, since the heart isn't directly involved in glucose homeostasis at all. The theory that I go with is that cardiac failure almost invariably involves congestion of the liver, as a result of a relative inability to pump blood onwards. The resultant backup of blood and interstitial fluid impairs the departure of blood from the liver. And, since the liver does the bulk of the body's gluconeogenesis and glycogenolysis, amongst the things that potentially reside in the blood leaving liver, of couse, is glucose.