The study by Piñero-Piloña et al. entitled “Idiopathic Type 1 Diabetes in Dallas, Texas: A 5-Year Experience” (1) reports on the features of 80 patients who present with diabetic ketoacidosis, the absence of islet cell antibodies, insulin autoantibodies, and GAD antibodies, or HLA antigens associated with type 1 diabetes. The authors then describe the phenotypic characteristics of 54 patients who had follow-up data. When the study began, the patients had a mean age of 34.8 years and a mean BMI of 31.6 kg/m2 and had lost 12.8 kg body wt. All of the subjects reported type 2 diabetes in first-degree relatives, and 35 had acanthosis nigricans. At follow-up 5 years later, 21 were treated with oral agents or diet and the remainder with insulin. Of the subjects, 65% were of African origin, 30% were Hispanic, and the remainder were Native American. Piñero-Piloña et al. (1) state that “[i]diopathic type 1 diabetes has been described mostly in African-Americans but also in individuals from other ethnic groups,” citing among others a study (2) concerning diabetic ketoacidsosis in Apache Indians who clearly had type 2 diabetes.

Idiopathic type 1 diabetes is defined as diabetes not associated with autoantibodies but for which insulin treatment is required for survival, although an absolute requirement for insulin replacement therapy and ketoacidosis may be episodic (3). Thus, it is unclear why the authors believed that all of these subjects had idiopathic type 1 diabetes. Because 40% of the subjects were no longer being treated with insulin after 5 years, and only 5 of the 21 on oral agents and 4 of the 33 on insulin had a second episode of ketoacidosis, the evidence presented strongly suggests that the majority did not have type 1 diabetes. Unfortunately, the authors did not provide data on insulin or C-peptide levels after the initial acute episode of diabetic ketoacidosis; such data might have helped to differentiate between patients with type 1 diabetes and those with type 2 diabetes.

It is well established that adolescents and young adults with type 2 diabetes often develop ketoacidosis, which may be the event that leads to diagnosis (2,4). The characteristics (viz., high level of obesity, history of type 2 diabetes, occurrence of acanthosis nigricans in >60%, and lack of true insulin dependency) of the group of patients in the study by Piñero-Piloña et al. (1) do not, as the authors claim, indicate idiopathic type 1 diabetes, but instead clearly indicate that the majority of these patients had type 2 diabetes. Although some of the patients might have idiopathic type 1 diabetes, the title of the study as well as its interpretation and discussion are extremely misleading, causing the reader to believe it to describe the clinical characteristics of a series of patients with documented idiopathic type 1 diabetes. We believe that the majority of the patients described in this study have type 2 diabetes rather than idiopathic type 1 diabetes.

1
Piñero-Piloña A, Litonjua P, Aviles-Sonta L, Raskin P: Idiopathic type 1 diabetes in Dallas, Texas: a 5-year experience.
Diabetes Care
24
:
1014
–1018,
2001
2
Wilson CH, Krakoff J, Gohdes D. Ketoacidosis in Apache Indians with non-insulin-dependent diabetes mellitus.
Arch Intern Med
157
:
2098
–2100,
1997
3
The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus: Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus.
Diabetes Care
20
:
1183
–1197,
1997
4
Umpierrez GE, Casals MM, Gebhart SP, Mixon PS, Clark WS, Phillips LS: Diabetic ketoacidosis in obese African-Americans.
Diabetes
44
:
790
–795,
1995

Address correspondence to P.H. Bennett, MB, National Institute of Diabetes and Digestive and Kidney Diseases, 1550 E. Indian School Rd., Phoenix, AZ 85014. E-mail: [email protected].