[Severe hypoglycemia in diabetics with impaired renal function]

Reduction of renal function in patients with type 1 or type 2 diabetes is associated with a clearly increased risk of hypoglycemia. Main causes are an altered pharmacokinetics of insulin and oral antidiabetics and/or impaired renal glucose production. A knowledge of renal function is, therefore, essential for preventing hypoglycemia caused by antidiabetic treatment. But serum creatinine, most commonly used in general practice, is an imprecise indication of renal function. This investigation assessed the significance of a false estimation of renal function as a partial cause of severe hypoglycemia.

The study group consisted of 35 diabetics (21 females, 14 males; average age 61 years) who had been hospitalized because of an episode of severe hypoglycemia accompanied by loss of consciousness. Renal function was measured by serum creatinine and by creatinine clearance as calculated by the formula of Cockcroft and Gault. Also taken into account were HBA1c the antidiabetic treatment before and after discharge, and any additional medication.

Impaired renal function was established by the serum creatinine level in 9 patients and by calculated creatine clearance in 24. Compared with patients with normal renal function, those with renal failure were older (74.3 vs. 32.8 years), had more rarely undergone intensive insulin treatment (5 of 24 vs. 9 of 11) and had more commonly received ACE inhibitors (10/24 vs. 1/11). The insulin dosage at discharge had been reduced in 16 off 22 insulin-dependent patients in renal failure, and long-acting sulfonylurea preparation were discontinued or changed to gliquidone in the others.

This investigation indicates that false estimation of renal function from the level of serum creatinine is an important partial cause of hypoglycemia requiring treatment, especially in elderly persons with reduced muscle mass in whom renal function should be determined by calculating or measuring creatinine clearance.