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.
This patient was a 79-year-old man who presented with a 3-year history of hyperglycemia and a 1-year history of polydipsia. At the time of presentation, he had been in a hypodynamic state for 15 days. Three years previously, he was diagnosed with impaired glucose tolerance without any symptoms, but no treatment was provided. One year earlier, he developed polydipsia, hyperuresis, and cutaneous pruritus, and lost weight. His random plasma glucose concentrations increased to as high as 20 mmol/L. Consequently, he was started on aspart 30 (21 units before breakfast and 8 units before dinner) and metformin (0.5 g twice a day). One month previously, he visited our hospital because of complaints of recurrent midnight hypoglycemia, particularly at approximately 02:00 am. During that period, although an insulin injection was gradually reduced and subsequently discontinued, his glucose concentration still dropped to 3 mmol/L. Laboratory tests showed that C-peptide and insulin concentrations were above the normal range, and the insulin autoantibody test was positive. At that time, non-classical IAS was considered as the probable cause of repeated hypoglycemia, and treatment was changed to acarbose (50 mg three times a day). After 15 days, blood tests showed the following: fasting plasma glucose level, 3.71 mmol/L; anti-insulin antibody, > 45.4 U/mL; and insulin concentrations were 1567.44/1493.06/1370.20/1616.43/1812.01 pmol/L at 0/30/60/120/180 min and C-peptide concentrations were 3.41/3.68/3.95/4.56/4.51 nmol/L at 0/30/60/120/180 min during the OGTT, respectively. For treatment of IAS, prednisone therapy was started at 12 mg daily (4 mg per dose three time daily) then reduced to 8 mg daily after 2 weeks and to 4 mg per night 1 week later. The diabetes treatment plan was changed to human biosynthetic insulin injection (16 units per day), sitagliptin (50 mg per day), and voglibose (0.3–0.2 mg twice a day). Repeated laboratory tests showed the following: C-peptide concentrations were 0.73/1.67 nmol/L at 0/2 h, respectively, and the insulin concentration was 728.14 pmol/L at 0 h during the OGTT. The glucose concentration fluctuated between 7 and 12.9 mmol/L.