Adrenal Medullary Fibrosis in IDDM of Long Duration

We conducted a retrospective pathology study to determine whether subjects with long-standing insulin-dependent diabetes mellitus (IDDM) have abnormalities of the adrenal medulla compared with subjects with non-insulin-dependent diabetes mellitus (NIDDM) and nondiabetic individuals. Slides were scored from 0 (no fibrosis) to 3+ (complete fibrosis). Nineteen IDDM subjects aged 30-60 yr (mean +/- SE 44.9 +/- 2.5 yr) at autopsy and with duration of diabetes 13-45 yr (26.8 +/- 1.8 yr) were studied. Twelve NIDDM subjects aged 61-84 yr (73.3 +/- 2.5 yr) with duration of diabetes 17-33 yr (22.8 +/- 1.9 yr) were studied. Twenty-two nondiabetic subjects aged 32-77 yr (53.7 +/- 2.9 yr) were studied. Four of 19 (27%) IDDM subjects had moderate to severe fibrosis compared to 1 of 12 (8.3%) NIDDM subjects and 1 of 22 (4.5%) control subjects. Thirteen of 19 (68%) IDDM subjects had a score of 1, 2, or 3 compared to 3 of 22 (13.6%) control subjects (P less than .0005). There was an association between duration of IDDM and fibrosis score (r = .46, P less than .05) and between age and fibrosis score among IDDM subjects (r = .57, P = .01). No association between age or duration of diabetes and fibrosis score was observed for NIDDM or control subjects. Adrenal medullary fibrosis may be an anatomical correlate of the diminished epinephrine secretion that occurs in response to insulin-induced hypoglycemia in some IDDM subjects.