• Refraction changes are transiently present when there are rapid alterations in the blood glucose concentrations
• These are the results of osmotic changes in the lens.
  
  

2. Are there correlations between his abnormal blood chemistries and his other symptoms?

• When blood glucose exceeds the renal threshold, (usually around 180 to 200 mg/dl), there is polyuria with resulting osmotic diuresis. 
• This leads to contraction of extracellular fluid and and thirst mechanisms are activated; hence, polydypsia. 
• The urinary loss of glucose implies also energy loss, as each gram of glucose has 4.1 calories.
•  Weight loss results from negative caloric balance, plus mild dehydration. 
• Increased appetite as well as a sensation of fatigue are attributed to impaired nutrient utilization in the hypothalamus and peripheral tissues.
  
  

3. Calculate his approximate daily caloric needs. The patient is an accountant, and his daily exercise is limited to walking two blocks walking to and from the parking lot and his office.

• Ideal body weight can be calculated from several formulas (one for adult males suggests 110 pounds for 5 feet of height, and 5 pounds for each additional inch--for females it is the same, but at 100 pounds for 5 feet of height). 
• For an ideal body weight of 140 pounds needs can be approximately calculated by multiplying 10 calories per pound for basal requirements, plus 3 calories per pound for sedentary activity. (For moderate activity, 6 calories x pound; for intense activity, 9 calories x pound.) 
• Caloric needs in this patient are, consequently, about 1,800 calories per day. 
• For weight reduction, there should be about 500 calories of deficit a day, which should be subtracted from his daily needs.
  
  

4. Why did an 1,800 calorie a day diet fail to lower his body weight?

• Self-evident. Our prescription just matched his caloric needs. 
• He will need a deficit of 3,500 calories a week to lose, on the average, one pound weekly. 
• This theoretical calculation seldom is met, even in correctly reduced diets, because of broad variation in individual caloric needs, physiological reduction in basal metabolic rate as adapted to caloric restriction, and chronic discomfort associated with unsatisfied appetite.
  
  

5. Was insulin treatment at this time the only possible option?

• The patient was treated with 5 mg/day of glyburide, a sulfonylurea which increases endogenous insulin release.
•  However, the range of glyburide dose is from 2.5 to 20 mg/day. 
• Maximum dosages might have been effective where the lower initial dose was not. (This is a frequent error in so-called sulfonylurea failure.)
•  Furthermore, a new hypoglycemic agent, Metformin, which does not cause insulin release, but facilitates glucose utilization and reduces insulin resistance, may potentiate the effect of sulfonylurea and therefore postpone the need for added insulin.