Idiopathic type 1 diabetes in Dallas, Texas: a 5-year experience.

OBJECTIVE To describe the clinical course of individuals with idiopathic type 1 diabetes after a mean of 5 years from diagnosis and to compare glycemic control between those treated with diet and/or oral agents and those treated with insulin at follow-up. RESEARCH DESIGN AND METHODS Medical records of patients with new-onset diabetes, who presented with unprovoked diabetic ketoacidosis, were reviewed. A total of 54 of these individuals were traceable and had relevant data collected within the past 2 years. All patients had nonsusceptibility HLA haplotypes and no serological evidence of autoimmune type 1 diabetes. Most of these patients were male (41 men and 13 women), were non-Caucasian, were obese at the time of diagnosis (BMI 31.6 +/- 6.3 kg/m(2)), reported weight loss (12.8 +/- 9.8 kg), had a family history of type 2 diabetes, and had acanthosis nigricans. At follow-up, 33 patients were still taking insulin and 21 were on diet and/or oral-agent therapy. RESULTS Both treatment groups were similar in clinical presentation and demographics at diagnosis. After 4.8 +/- 1.6 years of follow-up, the 33 patients that were receiving insulin had a lower HbA(1c) than the 21 patients who were using therapies other than insulin (7.8 +/- 2.4 vs. 11.1 +/- 3.5%, P = 0.009; 95% CI 1.0-6.5%). There was a high correlation between change in weight and change in HbA(1c) at follow-up (r = 0.45, P < 0.001, n = 54). There were no differences in the rate of diabetes complications or in the episodes of recurrent diabetic ketoacidosis. CONCLUSIONS Idiopathic type 1 diabetes occurs more frequently in male African-American patients but also occurs in other ethnic groups. Patients with idiopathic type 1 diabetes who continued to use insulin had better glycemic control than patients using therapies other than insulin. Regained weight is a good clinical marker for improvement in glycemic control. Individuals with this type of diabetes should not be switched to therapies other than insulin.