Interactive diabetes case 13: Deterioration of glycemia in a 59-year-old patient with type 2 diabetes complicated by retinopathy, nephropathy, and neuropathy

CASE — A 59-year-old man with diabetes is referred to you because he is not achieving glycemic goals. Fourteen years ago, the patient was found to have a blood glucose level of approximately 300 mg/dL (16.7 mmol/L) on a routine examination. He was treated with a program of diet, exercise, and glipizide. The glucose level fell to the 110 to 140 mg/dL (6.1 to 7.8 mmol/L) range.

The patient relates that for the next eight years, "I avoided it all," following no regimen and taking no medication for diabetes. Three years ago, his glycated hemoglobin (A1C) was 13 percent. He developed proliferative diabetic retinopathy and had a total of 11 laser treatments to both eyes and a right vitrectomy. He also developed progressive nephropathy.

When his vision deteriorated, he saw a clinician and resumed care of his diabetes. He followed a diet, began to exercise, and started to take NPH insulin, currently 52 units every day at bedtime. The A1C fell to 7.4 percent over the next nine months.

In the last year, the glucose values, previously predictable, became erratic, with nearly normal glycemia on some days, inexplicable hyperglycemia on others, and occasional hypoglycemia before lunch. His most recent laboratory studies include a blood urea nitrogen (BUN) of 44 mg/dL, a serum creatinine of 2.7 mg/dL (estimated glomerular filtration rate [eGFR] 28.5 mL/min/1.73 m²), a potassium level of 5.3 mEq/L, an A1C of 9.7 percent, and 2+ proteinuria. He has aching pain in his legs, mostly at night, from his feet to the level of the mid-calf. Light touch sensation is diminished to the thighs. Vibratory sensation is absent at the great toes and reduced at the medial malleoli and tibial tubercles. Deep tendon reflexes are absent at the ankles and the knees.

He has had nausea, abdominal pain, and intermittent constipation in the last year.

He was evaluated for these symptoms on two occasions. Laboratory studies revealed normal values for the white blood cell count, liver function tests, and amylase and lipase. Supine and upright radiographs of the abdomen revealed stool in the colon, no evidence of obstruction or perforation, and no other significant abnormality. An upper gastrointestinal (GI) series revealed only mild esophageal dysmotility and mild gastroesophageal reflux but was otherwise within normal limits. There was no evidence of obstruction.

Two years ago, after developing dyspnea while climbing stairs, he was found to have extensive coronary artery disease and had a four-vessel coronary artery bypass graft. The patient's medications, in addition to insulin, include lisinopril 40 mg daily, hydrochlorothiazide 12.5 mg daily, aspirin 81 mg daily, metoprolol 25 mg twice a day, a multivitamin, a stool softener, and psyllium. The patient weighs 205 pounds, is 5 feet 8 inches tall, and has a body mass index (BMI) of 31.2 kg/m².

How would you manage the patient?

●You change the patient's insulin regimen from NPH 52 units every day at bedtime to glargine insulin 42 units at bedtime. (See "Interactive diabetes case 13: Deterioration of glycemia in a 59-year-old patient with type 2 diabetes complicated by retinopathy, nephropathy, and neuropathy – A1".)

●You change the patient's basal insulin regimen from NPH 52 units every day at bedtime to glargine insulin 42 units at bedtime. You also prescribe prandial (pre-meal) and correction doses of lispro insulin. Using the rule of 1500, you recommend a prandial dose of 1 unit for every 10 grams of carbohydrates at meals and a correction dose of 1 unit for every elevation of 30 mg/dL of blood glucose above 150 mg/dL. 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" and "Interactive diabetes case 13: Deterioration of glycemia in a 59-year-old patient with type 2 diabetes complicated by retinopathy, nephropathy, and neuropathy – A2".)

●You advise the patient to add a sliding scale of regular insulin before meals and at bedtime, starting with 2 units for a blood glucose of 201 to 250 mg/dL (11.2 to 13.9 mmol/L) and adding 2 units for each increment of 50 mg/dL (2.8 mmol/L; eg, 4 units for a blood glucose of 251 to 300 mg/dL [13.9 to 16.7 mmol/L]), up to a dose of 8 units for a blood glucose of 351 to 400 mg/dL (19.5 to 22.2 mmol/L). (See "Interactive diabetes case 13: Deterioration of glycemia in a 59-year-old patient with type 2 diabetes complicated by retinopathy, nephropathy, and neuropathy – A3".)

●You advise the patient to measure the blood glucose levels seven or eight times a day, both before and after meals and at 2 or 3 AM, with the intention of using a more complex insulin regimen with glargine insulin at bedtime and lispro insulin before meals. In the meantime, you recommend a trial of metformin 500 mg by mouth twice a day in an effort to improve glucose management before intensifying the insulin regimen. (See "Interactive diabetes case 13: Deterioration of glycemia in a 59-year-old patient with type 2 diabetes complicated by retinopathy, nephropathy, and neuropathy – A4".)