Interactive diabetes case 6: Uncontrolled diabetes in a 64-year-old patient treated with insulin

CASE — A 64-year-old female, a retired office worker, has persistently variable glucose values on multiple injections of insulin a day.

Three years ago, the patient was admitted to another hospital in diabetic ketoacidosis in the setting of an upper respiratory infection. She was started on insulin then and has been on insulin ever since, currently taking NPH insulin 20 units every morning and using a sliding scale of aspart insulin sporadically. Her blood glucose values are variable when checked twice a day, before breakfast and before dinner. Most fasting blood glucose values are in the 200 to 300 mg/dL (11.1 to 16.7 mmol/L) range, but some are in the 40 to 60 mg/dL (2.2 to 3.3 mmol/L) range. Blood glucose values before supper vary from 44 to 327 mg/dL (2.4 to 18.2 mmol/L), with no apparent pattern. She is having occasional nocturnal insulin reactions. The glycated hemoglobin (A1C) is 10.2 percent. The patient says she counts carbohydrates and avoids concentrated sweets. She is 5' 1" tall, weighs 111 pounds, and has a body mass index (BMI) of 21 kg/m².

What do you recommend?

●A 1200-calorie diet to reduce variability in the blood glucose levels. (See "Interactive diabetes case 6: Uncontrolled diabetes in a 64-year-old patient treated with insulin – A1".)

●The addition of metformin 500 mg orally twice a day before meals to reduce the peak glucose values. (See "Interactive diabetes case 6: Uncontrolled diabetes in a 64-year-old patient treated with insulin – A2".)

●A sliding scale of aspart insulin at breakfast based on the carbohydrate intake at that time to reduce fluctuations in the blood glucose level later in the day. (See "Interactive diabetes case 6: Uncontrolled diabetes in a 64-year-old patient treated with insulin – A3".)

●A redistribution of insulin. You reduce the morning dose of NPH insulin to 10 units before breakfast and add NPH insulin 4 units at bedtime. You also add a dose of aspart insulin before supper, based on the patient's estimated insulin-to-carbohydrate ratio of one unit for every 25 grams of carbohydrate and correction factor of one unit for every 70 mg/dL (3.9 mmol/L) of blood glucose above 120 mg/dL (6.7 mmol/L) (see "Interactive diabetes case 6: Uncontrolled diabetes in a 64-year-old patient treated with insulin – A4"). An approach to estimating the dose of short- and very short-acting insulins is discussed separately. (See "Interactive diabetes case 3: Hypoglycemia in a patient with type 1 diabetes – B2".)