In the book we discuss how high blood sugar is a powerful predictor of poor outcomes in hospital patients.
Well, Abby’s grandmom is in the hospital with pneumonia. She is being fed with intravenous glucose, and has developed high blood sugar – 160 mg/dl – despite provision of insulin.
Abby says the doctors aren’t concerned. But they should be.
High Blood Sugar Causes Pneumonia
High blood glucose and high insulin both suppress immune function. As a result, pneumonia rates are much higher in hospital patients with high blood sugar. If hyperglycemia helps cause pneumonia, it’s surely a danger in someone who already has pneumonia.
A recent paper investigating the health effects of high blood sugar during total parenteral (meaning intravenous) nutrition gives us a quantitative assessment of the risks of elevated blood sugar. 
They report that pneumonia was the number one consequence of elevated blood sugar from intravenous feeding:
In multivariate analysis adjusting for age, sex, and history of diabetes, the blood glucose within 24 h of TPN >180 mg/dl was associated with increased risk of pneumonia (OR 3.6, 95% CI 1.6–8.4) and acute renal failure (2.2, 1.02–4.8 1) compared with patients with blood glucose <120 mg/dl. 
In other words: If 24 hours after intravenous feeding is started, blood glucose rises over 180 mg/dl, the likelihood of subsequently contracting pneumonia is increased 3.6 fold.
Abby’s grandma had blood glucose of 160 mg/dl, which is still at elevated risk :
Here the measure is mortality, not pneumonia, but we can see that blood glucose in the range 150-180 mg/dl 24 hours after initiation of TPN is quite a bit more dangerous than blood glucose levels below 150 mg/dl. Mortality rates are almost 50% higher.
This is not a new finding:
TPN therapy has been associated with increased risk for infections and mortality (2,10–13). The increased risk of complications appears to be related, among other factors, to the development of hyperglycemia (4,14). Observational studies have reported a 33% mortality rate in TPN patients who developed hyperglycemia (15), as well as an increased risk of cardiac complications, infections, systemic sepsis, and acute renal failure (3,4,6). In agreement with these reports, we found a strong correlation between TPN-induced hyperglycemia and poor clinical outcome. 
Some of the reasons hyperglycemia is dangerous involve immune suppression:
The mechanisms underlying the detrimental effects of hyperglycemia relate to alterations in immune functions and inflammatory response (16,17). Hyperglycemia impairs leukocyte function, phagocytosis, and chemotaxis (18). Hyperglycemia also increases counterregulatory hormones, inflammatory cytokines, and oxidative stress (16,17), which can lead to endothelial dysfunction and cardiovascular complications (17). 
Significance for Treatment
Patients who need intravenous feeding, in pneumonia cases presumably due to high choking risk or need for oxygen, have great difficulty avoiding negative health consequences. But the risks of intravenous feeding are increased by suboptimal formulations that have too much sugar and too much omega-6 polyunsaturated fat. Such formulations can strongly suppress immune function, especially if they produce hyperglycemia.
I hesitate to second-guess doctors who are on the scene and privy to case knowledge, but I think the evidence is pretty strong for the dangers of hyperglycemia. If Abby’s grandma has enough muscle and fat, fasting and receiving parenteral water, vitamins, and minerals might be a better strategy. At a minimum, glucose provision should be reduced or insulin increased to reduce blood glucose levels.
Doctors are Enslaved to Faulty Practice Standards
The paper I cited is from 2010, but the dangers of hyperglycemia have been known for decades. Yet hospitals still commonly induce it.
Our current medical institutions seem to have left doctors terrified of deviating from standard practice, even if standard practice is known to be harmful. And new, better practices can’t be adopted until proven in costly clinical trials, even though the existing practices were adopted without such trials.
I wonder what Dr. House would do in Abby’s grandma’s case? And if Dr. House would do the right thing for the patient in defiance of standard practice, how long would he keep his medical license or his malpractice insurance?
 Pasquel FJ et al. Hyperglycemia during total parenteral nutrition: an important marker of poor outcome and mortality in hospitalized patients. Diabetes Care. 2010 Apr;33(4):739-41. http://www.ncbi.nlm.nih.gov/pubmed/20040658.