SPECIAL SITUATIONS :-

Brittle diabetes

Treating type 1 diabetes is beset with a number of problems. The major amongst these is brittle diabetes, where the patient has intermittent very highs and very lows. These patients either have marked and often incapacitating excursions of blood glucose levels on daily basis or have frequent decompensation in their glycemic control often with recurrent ketoacidosis or hypoglycemia that significantly interferes with their lifestyles. Of particular concern is the apparent randomness of the blood glucose excursions, which do not show any diurnal pattern or predictable response to changes in diet or exercise. The problem has multiple causes. Insulin resistance with high titers of circulating insulin antibodies causing abnormalities in the kinetics of insulin action is one such cause. However, with use of human insulin and insulin analogues such as Lispro insulin, this has been relatively uncommon. More common however, are abnormalities in glucose counter-regulation such as Somogyi and Dawn phenomenon and hypoglycemia unawareness. Chronic undiagnosed infections, especially pulmonary tuberculosis is one such setting and underlying hormonal disorders such as acromegaly, glucocorticoid therapy, thyroid dysfunction, isolated or multiple pituitary deficiency and pheochromocytoma need exclusion. Gastroparesis can interfere with nutrient absorption and effect glycemic control. Poor injection technique and/or confusion by the patient as regards to the times of the dosages of insulin are often implicated. Of particular importance are psychosocial problems that lead to factitious disease (surreptitious administration of insulin, with no obvious gain or motive). Manipulative behavior is often seen in adolescents and poor glycemic control is often associated with eating disorders such as bulimia and anorexia nervosa. Patients concerned about weight gain in relation to insulin therapy discover that they can lose weight by ignoring their insulin injection

Brittle diabetes is best managed by a detailed history and careful physical examination by a physician who is familiar with these problems. Appropriate investigations, psychological evaluation and patient's dietary and exercise habits have to be adequately evaluated. If necessary, the patient should be hospitalized for stabilization and investigations. Most such cases can be controlled with MDI regimes and use of short acting insulin analogues such as Lispro insulin, after treating the precipitating or aggravating factors. Continuous subcutaneous insulin infusion may be required in a subset of these patients. Behavioral therapy and psychotherapy may be of additional help.

Hypoglycemic Unawareness

Though this problem is infrequently encountered in the pediatric age group, one has still to be concerned as hypoglycemia can be particularly debilitating in the young child. Usually this complication develops five to ten years after diagnosis of type 1 diabetes and is due to impairment of the counter-regulatory response of noradrenaline, adrenaline and glucagon. The prevalence of deficient adrenaline secretion in-patients with long standing diabetes may be as high as 40% (15) and is usually due to associated autonomic neuropathy. This problem is most often encountered with intensive insulin therapy and often resolves when the intensive regimes are discontinued. In such patients, higher targets for blood glucose control should be set (fasting and premeal blood glucose levels up to 150mg/dl).

REVERSE SPLIT INSULIN

Certain patients tend to have high pre dinner and post dinner blood glucose values, with normal values at other times. In such cases, either intermediate acting insulin may be given prior to lunch or a reverse split mixture with 30% intermediate acting and 70% regular insulin may be given at the same time. Such insulins, as mixtures of NPH and lyspro, are likely to be used in future. Use of lyspro and aspart insulin results in good postprandial blood glucose regulation but poor inter-prandial glycemic control. Hence, 20-30% of intermediate acting insulin with lyspro at each meal, particularly at breakfast and lunch, in the form of reverse split insulin will prevent inter-prandial blood glucose rise. The usual mixed insulin (30-50% regular and 70-50% NPH) is the more suitable insulin at pre-dinner time.