A 13-year-old girl has been observed by her parents to be eating and drinking a lot of junk food and carbonated beverages for the past 2 months. In spite of this diet she appears to be getting thinner. Her mother takes her to the physician. On physical examination her temperature is 37 C, pulse 74/min, respiratory rate 20/min, and blood pressure 90/60 mm Hg. She has peripheral muscle wasting. She is 165 cm tall and weighs 47 kg.

Laboratory studies show Hgb 13.2 g/dL, Hct 40%, MCV 94 fL, platelet count 290,200/microliter, WBC count 6990/microliter, sodium 149 mmol/L, potassium 4.9 mmol/L, chloride 113 mmol/L, CO2 9 mmol/L, glucose 394 mg/dL, creatinine 0.7 mg/dL, total protein 6.2 g/dL, albumin 4 g/dL, and total bilirubin 1.1 mg/dL. A urinalysis shows pH 6, sp gr 1.011, glucose 4+, protein negative, blood negative, and ketones 4+.

Questions:

4.1 What is the diagnosis?

She has type I diabetes mellitus.

4.2 What therapy is indicated?

Since there is an absolute lack of insulin with type 1 diabetes mellitus, she requires insulin therapy, carefully monitored with blood glucose measurements, to adjust for diet and exercise.

Insulin therapy is typically a combination of a short acting (e.g., "regular") insulin with an intermediate acting (e.g., NPH) or long-acting insulin.

The long-acting insulin known as insulin glargine (trade name Lantus ®) has continuous, "peakless" action that mimics natural basal (background) insulin secretion. Although it provides a long-lasting effect, insulin glargine's onset is within 2 to 4 hours, similar to NPH insulins, but faster than extended zinc insulins. Insulin glargine is less likely to be complicated by hypoglycemia, especially during the night. Giving it at an evening meal time is an important advance for the treatment of children in preventing nocturnal lows.

Many people use both rapid- or short-acting insulins, and insulin glargine can be used with shorter-acting insulins to mimic natural insulin secretion. Because insulin glargine has no distinct peak, injections of rapid-acting insulin must be given before all meals to provide bolus coverage for food intake. Both types of insulin are clear in appearance, so it is very important that your patient choose the correct dose from the correct vial of insulin...AND insulin glargine must NOT be mixed with any other type of insulin and should NOT be administered intravenously. (One distinguishing factor is that insulin glargine vials are taller and narrower than those of other insulins.) Insulin glargine can be injected any time during the day, as long as it is at the same time each day.

Reference: Hirsch IB. Drug therapy: insulin analogues. New Engl J Med. 2005;352:174-183.

4.3 She is poorly adherent to therapy. She eats whatever she wants. What options can be employed? Her Hgb A1C is still only 5.8%. Why is this possible?

Key point: Her hemoglobin A1C value tells us nothing about what she is actually eating. She could be eating a lot with this value (honeymooning, purging after eating, taking extra insulin after eating large meals, having frequent hypoglycemic episodes due to an inadequate insulin regimen, not eating after taking insulin, or a lot of exercise), very little or just the right amount. The best approach to finding out what she is eating is to do a behavioral assessment of her diet (see comments above).

4.4 What kinds of information would you gather or what assessments would you conduct to advise this young woman and her family about her diet?

Key point: Many components of the diet are important for diabetes care, including the frequency of eating, amount eaten, types of food eaten, and insulin and exercise in relationship to eating. A detailed assessment of this information is needed to identify areas of change. Also needed is an assessment of the patient's and family's knowledge of diet and its relationship to glycemic control. For example, she may consume a "sports drink" and she assumes this is healthy. She may not know it is loaded with sugar which will raise her blood sugars. She may not understand how to adjust her insulin accurately in relationship to meals. Or she could be very worried about hypoglycemia and not giving enough insulin in relationship to meals. Developmental issues should be considered--she is only 13; perhaps her parents are giving her too much responsibility for her diabetes care. Her family environment could play a role: family members may be unwilling to change their diet, making it more difficult for her to manage her diabetes (e.g., everyone else in the family continues to drink regular coke which is "stocked" in the refrigerator while her "diet" coke if stocked out of the way in the pantry). Peers may also play a role--she may not want to act different than her friends and, as a consequence, continues to eat foods that are not consistent with good diabetes care.