A 46-year-old woman with type 2 diabetes and depression was admitted to our hospital due to an insulin overdose. She had received prescriptions for metformin 500 mg and 70 U of insulin per day. She had been in good glycemic control and her HbA1c level was 5.4 %. On the day of admission, she was transported by ambulance one hour after she had self-administered 3000 units of insulin (2100 U of Lispro plus 900 U of glargine). She was admitted to the hospital to prevent subsequent severe hypoglycemia. She was treated by an intravenous infusion of glucose and oral ingestion of glucose and meals. A measurement of her serum insulin level revealed an exponential decrease from 31975 μU/ml at one hour after the insulin injection to 20903 μU/ml at 6 hours and 9370 μU/ml at 9 hours. The final supplementation of oral glucose was 141 hours after injection. An analysis of the patient's blood glucose concentration by continuous glucose monitoring revealed rapid fluctuations as a sawtooth pattern in response to the administration of glucose. Although changes in the serum insulin level may be helpful for estimating the recovering time from hypoglycemia, frequent measurements of the blood glucose concentration are necessary for patients who overdose on insulin.

View full abstract

A 51-year-old woman was admitted to our hospital due to nausea and upper abdominal pain. She had a consciousness disorder and tachycardia. Her laboratory data showed hyperglycemia (plasma glucose level: 694 mg/dl), ketosis (total blood ketone body level: 15.4 mmol/l) and acidemia with preserved insulin secretion and negative findings for anti-GAD antibodies. She was diagnosed with diabetic ketoacidosis, and insulin therapy was commenced. She had a nodular goiter in the left lobe of her thyroid (3×4 cm) in addition to hyperthyroidism (TSH <0.01 μIU/l; Free T₃ 3.04 pg/ml). Thyroid autoantibodies were negative; however, ¹²³I thyroid scintigraphy revealed a hot nodule corresponding to the tumor. Plummer disease was diagnosed and hemithyroidectomy was performed. After the surgery, the patient's glycemic control was excellent and the insulin therapy was withdrawn. It is well known that the development of diabetic ketoacidosis may be accelerated by hyperthyroidism mostly caused by Basedow's disease. Clinicians should be aware of Plummer disease as a cause of hyperthyroidism during episodes of diabetic ketoacidosis in patients with type 2 diabetes mellitus.

View full abstract

An 80-year-old woman was admitted because of a frequent loss of consciousness and hypoglycemic episodes. She had developed diabetes mellitus in 1978 and was started on insulin treatment in 1990 and multiple daily injections in 2005. Her glycemic control during these periods was moderate (HbA1c: 7 % to 9 %). Bisoprolol at a dose of 2.5 mg for hypertension was administered starting in 2006. In 2014, she suffered from frequent episodes of loss of consciousness and vomiting (two to three times per month) within three months before admission, in addition to frequent hypoglycemic episodes. On the second hospital day, she experienced loss of consciousness and vomiting, and severe bradycardia (heart rate: 30 beats per minute) was observed. The blood glucose level at that time was not low (221 mg/dl). An electrocardiogram showed sinus arrest, considered to be caused by bisoprolol, and temporary cardiac pacing was needed. Pacing became unnecessary the next day, and no further loss of consciousness or vomiting dependent on severe bradycardia occurred. Since polypharmacy is common in the treatment of diabetes mellitus among elderly patients, it is important to check medications thoroughly when a patient suffers from new symptoms.

View full abstract

An 83-year-old woman was admitted to our hospital because of a consciousness disturbance caused by hypoglycemia. She had a history of distal pancreatectomy for the treatment of insulinoma at 57 years of age. A 72-hour fast test induced hypoglycemia and relatively high levels of both insulin and C-peptide; therefore, so-called hyperinsulinemic hypoglycemia and recurrence of insulinoma was suspected. However, no pancreatic tumors were detected on imaging examinations and the blood glucose response to octreotide was atypical. We re-evaluated the pathological findings of a previously resected pancreatic specimen. The main findings were hyperplasia of islet cells, without tumorous changes. These findings are identical to nesidioblastosis. We examined the responses of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) in the plasma to an oral load of 75 g of glucose. Both the basal and peak levels of GLP-1 were higher than those previously reported. Treatment with diazoxide was effective in preventing hypoglycemia by reducing insulin secretion. Several cases of nesidioblastosis developing after gastrectomy have been reported. The current patient had no history of gastrectomy. Hypersecretion of GLP-1 played a certain role in the development of beta-cell hypertrophy in this case. It is expected that further mechanisms will be clarified in the future.

View full abstract

Insulin degludec is a new generation of long-acting insulins. It produces a constant, peakless kinetic profile that mimics physiological basal insulin secretion. This insulin analogue is thought to be an ideal basal insulin because of its low variability and reduced frequency of hypoglycemic events. However, we herein report two cases of type 1 and type 2 diabetes with severe hypoglycemia induced by insulin degludec. In both cases, the fasting blood glucose levels decreased to hypoglycemic levels over many months, although no episodes of hypoglycemia detected by the patients. It has been reported that insulin degludec may show lower rates of hypoglycemia compared to other long-acting insulin analogues in clinical trials; however, whether this is true in the clinical setting is unknown. Due to the limited clinical experience with insulin degludec, physicians administering this drug should pay careful attention to the risk of hypoglycemic events, as with other anti-diabetic drugs.

View full abstract

We herein report the first case of an older woman with type 1 diabetes who attempted suicide by subcutaneously injecting herself with an overdose of insulin degludec and lispro. A 70-year-old woman being treated for type 1 diabetes and depression was admitted to our hospital three hours after attempting suicide via the injection of 300 U of degludec and 300 U of lispro. On admission, she was drowsy, and her capillary blood glucose level was less than 30 mg/dl, while her serum insulin level was remarkably elevated at 2972.1 μU/ml. We closely monitored her serum insulin and blood glucose levels and administered intravenous glucose as needed, and she subsequently recovered from hypoglycemia approximately 30 hours after the insulin overdose. However, because her serum insulin level was still 1,327.0 μU/ml at 36 hours after the overdose, intravenous glucose injections were continued for five days to prevent hypoglycemia. This is the first case of prolonged hypoglycemia caused by an insulin degludec overdose in a patient with type 1 diabetes. Monitoring the daily plasma insulin level was useful for predicting and preventing severe hypoglycemic episodes in our patient. The present case highlights the need for a longer period of treatment with intravascular glucose infusion in patients with an overdose of insulin degludec.

View full abstract

In addition to self-monitoring of blood glucose (SMBG), continuous glucose monitoring (CGM) is used for the evaluation of changes in blood glucose (BG) levels. The aim of this study was to evaluate the precision of glucose measurement using professional CGM (Pro-CGM) and personal CGM (Per-CGM) devices. Pro-CGM and Per-CGM devices were simultaneously attached to Japanese patients with type 1 diabetes mellitus, the sensor glucose (SG) readings were obtained, and their correlations with the BG levels obtained by SMBG were evaluated. Eight patients with type 1 diabetes mellitus were included in this study. The BG levels were measured by SMBG at 131 time-points, and the values were compared with the SG readings obtained simultaneously by the Pro-CGM and Per-CGM devices. Strong positive correlations were found between both the SG readings obtained by the Pro-CGM and Per-CGM devices and the BG levels obtained by SMBG. The mean absolute deviation between the SG readings obtained by the Pro-CGM device and the BG level was 12.3±13.8 %, and that between the SG reading obtained by the Per-CGM device and the BG level was 13.7±12.6 %; thus, the sensor precision of the two types of CGM appeared to be approximately the same. Both the Pro-CGM and Per-CGM devices showed correlations with the BG levels in Japanese patients with type 1 diabetes mellitus and are therefore considered to be useful for the evaluation of changes in the BG levels.

View full abstract