Abstract
BACKGROUND
Maternally inherited diabetes and deafness (MIDD), which is seen in 0.5% to 2.8% of patients with type 2 diabetes mellitus, is related to a point mutation at position 3243 of mitochondrial (mt) DNA. Its clinical description is incomplete.
OBJECTIVE
To study the clinical presentation and complications of diabetes in patients with MIDD and to identify clinical characteristics that may help select diabetic patients for mtDNA mutation screening.
DESIGN
Multicenter prospective descriptive study.
SETTING
16 French departments of internal medicine, diabetes and metabolic diseases, or both.
PATIENTS
54 patients with type 2 diabetes mellitus and the mtDNA 3243 mutation.
MEASUREMENTS
Characteristics of diabetes, metabolic control (glycosylated hemoglobin level), complications of diabetes, and involvement of other organs.
RESULTS
On average, patients with MIDD were young at diabetes onset and presented with a normal or low body mass index. None were obese. Seventy-three percent of probands had a maternal family history of diabetes. Diabetes was non-insulin-dependent at onset in 87% of patients; however, 46% of patients had non-insulin-dependent disease at onset but progressed to insulin therapy after a mean duration of approximately 10 years. Neurosensory hearing loss was present in almost all patients. Eighty-six percent of patients who received an ophthalmologic examination had macular pattern dystrophy (a specific retinal lesion). Forty-three percent of patients had myopathy, 15% had cardiomyopathy, and 18% (9 of 51) had neuropsychiatric symptoms. Although the prevalence of diabetic retinopathy was 8% among patients who received an ophthalmologic examination, lower than expected after a mean 12-year duration of diabetes, prevalence of kidney disease was 28%. This suggests that a specific renal involvement was the result of mitochondrial disease.
CONCLUSIONS
Maternally inherited diabetes and deafness has a specific clinical profile that may help identify diabetic patients for mtDNA testing.
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