High Blood Sugar in the Elderly

Hi,
It is impossible: The sugar level in the morning (after night fast) has to be lower than at the evening and increases while eating.   In any case 305 sugar is too high and that means that her blood is too viscouse (doesn't flow well) and hence the blood might not be able to reach the tiny vessels at some of her important organs (eyes, kindney, etc....). 
Best regards,

Normal blood sugar levels are between 80 to 120. Get you grandmother to a doctor or to the hospital as soon as possible. Wide swings in blood sugar levels are very problematic. She needs to be stabilized.

Yes,  this is dangerous. The study, which was conducted in collaboration with researchers from the Stockholm Gerontology Research Center, included 1173 people aged 75 and older. They found that the risk of developing dementia was highest in people with pre-diabetes who had high blood pressure as well."... School of Medicine have discovered that older individuals with unstable blood sugar levels are more likely to suffer from memory impairment and other ..." The Glycaemic Factor: How to Balance Your Blood Sugar (Overcoming Common Problems)