Good Long-Term Quality of Life Without Diabetic Complications With 20 Years of Continuous Subcutaneous Insulin Infusion Therapy in a Brittle Diabetic Elderly Patient

More than 20 years have passed since continuous subcutaneous insulin infusion (CSII) was proposed as a means of controlling glycemia in insulin-dependent diabetes by Pickup et al. (1). Since that time, the American Diabetes Association has approved CSII as an effective means of implementing intensive diabetes management, with the goal of achieving near normal levels of blood glucose and improved lifestyle flexibility (2). Although the effect of long-term control with CSII with regard to complications has been studied (3–5), the duration of these studies does not exceed 20 years. After 20 years of diabetes, nearly all patients with type 1 diabetes and 60% of patients with type 2 diabetes have some degree of retinopathy (6), and most have other diabetic complications, including macrovascular disease (7).

We hereby report a patient with brittle diabetes with good long-term quality of life without any diabetic complications who was treated by CSII for 20 years (8,9). The patient is a 72-year-old woman (height 147 cm, weight 45.5 kg, and BMI 21 kg/m²). Her blood pressure was 104/60 mmHg. The subject’s type 1 diabetes was initially manifested by a diabetic coma at 49 years of age (in 1979). At 51 years of age, she was treated by CSII with short-acting neutral buffered insulin, using the Nipro (Osaka, Japan) apparatus because her daily activities were disrupted due to frequent severe hypo- and hyperglycemic coma (mean amplitude of glycemic excursion [MAGE] 270 mg/dl) and because of the poor glycemic control (HbA_1c 11.5%) achieved with multiple-dose insulin injections (8). Although the therapy was effective (MAGE 50 mg/dl and HbA_1c 7%), at 55 and 59 years of age, hypoglycemic coma frequently occurred. The occurrence of coma was resolved after the patient was treated with thyroid and glucocorticoid hormones because she had hypothyroidism due to chronic thyroiditis and isolated ACTH deficiency. Alternative therapy with short-acting neutral nonbuffered insulin induced severe hyper-and hypoglycemic coma (MAGE 170 mg/dl) (9). Therefore, the therapy was switched to CSII with short-acting acidified insulin, and the patient is now using lispro insulin. The basal insulin infusion rate was 0.3 units/h, and bolus injections at breakfast, lunch, and dinner were 5, 2, and 3 units, respectively. This regimen was effective. MAGE and HbA_1c were maintained at 30–40 mg/dl and 4.9–7.1%, respectively. In this case, a wide swing of blood glucose concentrations was worsened by deficiency of counterregulatory hormones and the nonbuffered insulin used in CSII. At 66 years of age, the patient was prescribed an oral ACE inhibitor and Ca²⁺ antagonist for hypertension. At 69 years of age, she was treated with antibiotics for bronchial ectasia.

The patient is now 72 years of age, and at the time of this study (2001), her fasting blood glucose was 100 mg/dl (normal <110 mg/dl), her HbA_1c was 4.8% (normal 4.5–5.8%), and her MAGE was 20 mg/dl. The subject’s urinary albumin excretion rate was 7.2 mg/day (normal <25 mg/day) or <4 μg/mg creatinine (normal <30 μg/mg creatinine). Her tendon and Achilles’ reflexes were normal, and her nerve conduction velocities in the distal motor and sensory nerves were 48 and 52 m/s, respectively (normal >40 m/s). The minimal latency of F-wave in the ulnar nerve was 21.8 ms (normal <30 ms). The patient’s heart rate variation at rest was 3.1% (normal 1.1–3.5%). Seven-field stereo fundus photographs showed no abnormality. The concentrations of total, HDL, and LDL cholesterol and triglycerides were 237, 76, 147, and 58 mg/dl, respectively (normal <200, >40, <130, and <150 mg/dl, respectively). The findings of an exercise tolerance test, using conventional electrocardiogram (treadmill test), were negative, and carotid intima-media thickness was 0.8 mm (normal <1.0 mm) (10). Bone mineral density at the lumbar spine (L2–4) was 8.79 g/cm² (normal 8.45–8.70 g/cm²). All of these findings indicate that this patient has not experienced complications of chronic diabetes over the 20-year period of treatment (7).

The reason for the underlying absence of chronic diabetic complications is that this patient has maintained good glycemic control, as indicated by HbA_1c levels that were sustained at <7% for 20 years. In addition, although there is not a precise definition of brittle diabetes, this case may be considered as one of brittle diabetes (11). The outcome of patients with brittle diabetes is miserable (12). However, the experience with this patient indicates that CSII can stabilize wide swings in blood glucose concentrations and maintain good quality of life over a long period of time while attempting to understand the specific etiology of brittle diabetes (12,13). Moreover, this case shows that CSII is useful in elderly patients, although its safety has not been demonstrated in elderly patients (2).

In conclusion, this case demonstrates that CSII can be tolerated as well as effective in maintaining a good quality of life without diabetic complications over a long period of time (20 years in a type 1 diabetic patient). Our experience suggests that even though the patient has the brittle type of diabetes and is elderly, if HbA_1c level can be maintained at <7%, as indicated by the study of the Diabetes Control and Complications Trial Research Group (4), chronic diabetic complications can be avoided.