[Insulinoma].
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Biomedical subjects
Publications and source records attributed to Junichi Yokoyama.
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In 1996, we designed a randomized multicenter study to assess the effects of small doses of insulin on beta cell failure in slowly progressive type 1 diabetes (the Tokyo Study). We report here the preliminary results of this study. Glutamic acid decarboxylase 65 antibody (GADA)-positive patients were randomly divided into 2 groups: one group received insulin (Ins group), the other a sulfonylurea (SU group). Fifty-four patients (24 Ins group, 30 SU group) were analyzed at the end of a 4-year period. All patients underwent a 75 g oral-glucose test (O-GTT) every 6-12 months. The insulin-dependent stage was defined based on an integrated value of serum C-peptide levels on O-GTT ( summation operator CPR; sum of CPR at 0, 30, 60, 90, and 120 min) below 4.0 ng/mL. The summation operator CPR in the SU group decreased progressively from 22.0 +/- 10.6 to 11.3 +/- 7.5 ng/mL over the 48-month period (p < 0.001 vs. baseline). The summation operator CPR in the Ins group was unchanged. Among the SU group, 30% of subjects (9/30) progressed to IDDM, while 8.3% of Ins group subjects (2/24) progressed to IDDM (p = 0.087). With regard to the subjects who had a preserved C-peptide response ( summation operator CPR >/= 10 ng/mL), the proportion of SU group subjects who progressed to IDDM was significantly higher than that of the Ins group (7/28, 25% vs. 0/21, 0%, p = 0.015). Among subjects with a high GADA titer (>/=0 U/mL), 9/14 (64.3%) of the SU group, but only 2/16 (12.5%) of the Ins group, developed IDDM (p = 0.0068). As to those with a high GADA titer and a preserved C-peptide response, SU group subjects progressed to IDDM (7/12, 58.3%) more frequently than Ins group subjects (0/14, 0%) (p = 0.0012). In summary, our results suggest that small doses of insulin effectively prevent beta cell failure in slowly progressive type 1 diabetes. We recommend avoiding SU treatment and instead administering insulin to NIDDM patients with high GADA titer.
Slowly progressive insulin-dependent (type 1) diabetes mellitus (SPIDDM) is characterized by (1) late age of onset, with initial features of NIDDM and subsequent progression to insulin-dependent stage; (2) high predictive value of autoantibodies against glutamic acid decarboxylase (GADAb) and islet cell antibodies (ICA) for progression of beta cell failure; (3) less predominant T cell response, which may attack and eventually destroy beta-cells in affected pancreas. These findings may suggest a rationale for intervention to prevent slowly progressive beta cell dysfunction in this type of diabetes. We identified three independent risk factors for progression of beta cell failure in SPIDDM: (1) sulfonylurea treatment; (2) ICA-positive periods; and (3) initial body weight. We hypothesized that removal of the risk factors for further progression of beta cell dysfunction will have beneficial effects on intervention strategy in treating SPIDDM. In our pilot study, we used a small dose of insulin instead of sulfonylurea in the early stage of treatment of patients with SPIDDM. Insulin-treated SPIDDM patients had a sustained C peptide response (CPR), while most of sulfonylurea-treated patients progressed to an insulin-dependent state. We organized a randomized multicenter clinical trial to study early treatment to prevent the progression of beta cell dysfunction in SPIDDM (the Tokyo Study). It was demonstrated that early intervention with insulin therapy is an effective treatment modality in the early stage of SPIDDM patients who had preserved beta cell function at entry (integrated value of serum C peptide values at 0, 30, 60, 90, and 120 minutes; Sigma CPR >or= 10 ng/mL) and high GADAb (>10 U/mL). Preventive insulin treatment was ineffective in the patients who had diminished insulin reserve at entry (Sigma CPR < 10 ng/mL). Insulin intervention to preserve beta cell dysfunction in SPIDDM is effective and safe in patients with preserved beta cell function and high GADAb titers at the initiation of insulin.