Hypoglycemia in stable, insulin-treated veterans with type 2 diabetes: a prospective study of 1662 episodes

We evaluated the incidence, severity, and predisposing risk factors for hypoglycemic episodes in subjects with type 2 diabetes.

We conducted a prospective observational study of Southwest veterans with stable, insulin-treated type 2 diabetes who were randomly selected from pharmacy databases. Electronically recorded self-monitored blood glucose (SMBG) results were collected during 12 months of routine monitoring. We defined hypoglycemia as an SMBG reading < or =60 mg/dl. Subjects graded the severity of each hypoglycemic episode: 0=asymptomatic, 1=mild/moderate symptoms, 2=severe, with mental impairment or need for assistance. Subjects also reported any predisposing factors for each hypoglycemic episode.

We enrolled 344 subjects, mean (S.D.) age of 65.5 (9.7) years, 96.5% were men, and 35.2% were minorities. During an average follow-up of 41.2 (8.6) weeks, 176 subjects (51.2%) documented at least one hypoglycemic reading for a total of 1662 episodes. These subjects had a median of six (interquartile range 2-14.9) hypoglycemic episodes. The mean hypoglycemic blood glucose reading was 49.7 (7.5) mg/dl and the mean symptom score was 0.84 (0.45). Nearly 80% of episodes were symptomatic, 3.4% were severe. Subjects identified a cause for 45.2% of episodes: 53.3% of these were attributed to missing a meal, 23.8% to exercise, and 1.6% followed a medication increase.

A high proportion of stable, insulin-treated subjects developed hypoglycemic episodes, but severe hypoglycemia occurred infrequently. Medication increases were rarely identified as causing hypoglycemic episodes. Efforts to achieve tight glycemic control should recognize that patient behaviors commonly cause hypoglycemia.