This patient was a 71-year-old man who was admitted because of polydipsia and polyuria that had persisted for 8 years, as well as recurrent episodes of unconsciousness throughout this period. He was diagnosed with type 2 diabetes mellitus 8 years before admission. Acarbose was initially prescribed, but was switched to insulin aspart 30 (8–12 units twice a day) because of poor glucose control 5 years previously. Three months previously, the dose of insulin aspart 30 was gradually reduced to 4–10 units because of hypoglycemia. However, he had unexpected episodes of unconsciousness due to hypoglycemia 12 days before admission. Moreover, his symptoms were obviously relieved after food intake. He was subsequently treated with voglibose instead of insulin injections. However, the hypoglycemic symptoms continued to appear between 02:00 am and 03:00 am, despite the absence of other treatments. A laboratory examination showed the following: C-peptide values were 15.22/17.59/19.73/15.22 nmol/L at 0/1/2/3 h, and insulin concentrations were > 2089.5/> 2089.5/> 2089.5/> 2089.5 pmol/L at 0/1/2/3 h during the OGTT, respectively. The anti-insulin antibody test was also positive. His treatment regimen was changed to prednisone (5 mg three times a day), acarbose (50 mg three times a day), metformin (0.5 g twice a day), and glargine (12–18 units twice a day) for glucose control. Insulin injections were also gradually discontinued. Following this treatment, he showed improved glucose control. Laboratory tests during a recent follow-up showed the following: C-peptide levels of 0.77/2.40 nmol/L at 0/2 h and insulin levels of 430.13/1350.21 pmol/L at 0/2 h during the OGTT, respectively.
This patient was a 79-year-old man who had a 10-year history of hyperglycemia in addition to fluctuating glucose concentrations for more than 1 year. This was accompanied by diabetic nephropathy as well as a history of gout for more than 30 years. His glucose concentrations were initially well controlled with metformin after diagnosis of type 2 diabetes mellitus. A subcutaneous insulin pump (lispro) was recently added to his treatment regimen for renal insufficiency, and metformin was gradually changed to Humulin R (6–4-4 units, three times a day) combined with glargine 12 units a day. Thereafter, he had recurrent midnight hypoglycemia and daytime hyperglycemia, with blood glucose concentrations up to 20 mmol/L. Therefore, he was treated with acarbose (50 mg three times a day) instead of insulin injections. At this time, his C-peptide values were 5.45/6.94/6.94/7.89/7.17 nmol/L at 0/0.5/1/2/3 h, respectively (normal range: 0.27–1.28 nmol/L). His insulin concentrations were > 1000.00/> 1000.00 pmol/L at 0/2 h, respectively (normal range: 13–161 pmol/L), during an oral glucose tolerance test (OGTT), his HbA1c concentration was 10.2%, and an anti-insulin antibody test was positive (reference level: < 0.4). His glucose concentrations still fluctuated between 11 mmol/L and 22 mmol/L in the daytime, while hypoglycemia occurred at night. Subsequently, acarbose (100–100-50 mg three times a day) and sitagliptin (50 mg per day) were prescribed for symptom management, and his glucose concentrations returned to the normal range. Laboratory findings at a 1-year follow-up showed an HbA1c concentration of 7.0%, insulin concentrations of 138.53/733.40 pmol/L at 0/2 h, and C-peptide concentrations of 1.35/2.21 nmol/L at 0/2 h, respectively.