[Clinical implication of serum insulin determination. Diagnosis and prognosis in patients with apparent secondary failure of treatment with sulfonylureas (author's transl)].

Serum insulin was measured after maximal stimulation in 213 patients with apparent secondary failure of treatment with sulfonylureas. The maximal increase of serum insulin was 327% of baseline in patients treated with oral drugs alone and 175% in patients switched to insulin. The control of diabetes in the patients treated with oral drugs alone was investigated 2 to 3 years later by a questionnaire and correlated to the insulin values measured earlier. Following conclusions were drawn: Sulfonylurea treatment is indicated if the increase of serum insulin is more than 300%. If the increase of serum insulin is below 200%, insulin treatment is necessary now or in the near future. The determination of serum insulin after maximal stimulation in patients with apparent secondary failure of sulfonylurea treatment has a diagnostic as well as a prognostic value.