We studied the insulin sensitivity in 5 normal subjects and 5 subjects with impaired carbohydrate tolerance using the glucose controlled insulin infusion system (BIOSTATOR). During a fixed glucose infusion rate of 2 mg/kg b.w./min, the computer program was set to maintain the plasma glucose concentration at 4.44 mmol/l. The ratio of infused exogenous insulin to infused glucose served as a measure of insulin sensitivity. Calculating the average insulin glucose ratio for 24 hours, the mean values amounted to 3531 and 9319 ng/gm (p less than 0.01) in subjects with normal and impaired carbohydrate tolerance, respectively, indicating that insulin resistance is the main cause of decreased glucose utilization in the latter group. Circadian rhythms of insulin sensitivity occur in both groups in a similar fashion. The insulin sensitivity was higher in the afternoon (1200-1800) as compared to the night. Thus, diurnal variations in insulin sensitivity are independent of disturbances of glucose metabolism.

Islet cell cytoplasmic antibodies (ICA), islet cell surface ( ICSA ) antibodies, HLA phenotypes, glucose tolerance, insulin secretion, and insulin sensitivity were studied in 16 twins of insulin-dependent diabetics as well as in 21 subjects with impaired glucose tolerance (IGT). 60% of the identical twins and 40% of the non-identical twins were ICSA -positive. The prevalence of ICSA in control persons was only 5%. ICA were found in all identical twins and in half of the non-identical twins. However, ICSA and ICA results were concordant in only 46% of the whole group of twins. There was no correlation between ICSA and either insulin secretion or insulin sensitivity. In the IGT subjects exhibiting low and normal insulin responses ICSA were observed in 67% and 23%, respectively. A high proportion of twins, but not of IGT subjects, had HLA DR3 or DR4 antigens which seem to confer genetic susceptibility to the development of IDDM. In the majority of DR3/DR4 twins, ICSA were also present. This might support the hypothesis of genetically-based autoimmunity, although the precise relationship between HLA and islet cell antibodies has to be clarified in a prospective study.

We studied glucose concentration of breast milk of nursing diabetic mothers and its possible relationship to the quality of metabolic control. Eleven Type 1 (insulin-dependent) diabetic mothers and 11 age-matched control subjects were included in the study. Although a near-normoglycemic control of diabetic mothers was accomplished by intensified insulin treatment, the HbA1 value was significantly higher in comparison to non-diabetic mothers (8.1 +/- 0.9% versus 6.2 +/- 0.5%; p less than 0.01). Regardless of this, the glucose concentration of breast milk did not differ between diabetic mothers and that of non-diabetic women (0.68 +/- 0.50 mmol/l versus 0.66 +/- 0.55 mmol/l). No correlation exists between glucose concentration of breast milk and relevant blood glucose concentration as well as glycosylated haemoglobin A1 of the mother. In conclusion, our data support the view that breast-feeding of infants of diabetic mothers is not associated with an increased offer of glucose and thus not being of importance as a possible mechanism to sustain a hyperinsulinemic state in the newborns.

Forty diabetics (19 men, 21 women; mean age 54 [41-66] years) with secondary failure of sulfonylurea treatment, were assessed by questionnaire (psychological-neurological state; scale of well-being; attitude towards achievement, and psychological aspects of performance), both before and four months after being put on insulin treatment, as to the way in which they experienced and dealt with the illness. Before the onset of insulin treatment, a general decrease in performance was the predominant symptom (29 patients), while only about half of the patients declared diabetes-specific symptoms. The necessity of insulin administration was experienced by 34 patients as a severe crisis in their chronic illness. Anxiety over failure in the act of injection (30 patients), as well as fear of the consequences regarding their job (25 patients) and of restriction in the personal sphere (31 patients) were the chief reasons for their dislike of insulin treatment. Four months after starting insulin treatment these anxieties had largely disappeared. The only remaining fear was that the necessity of insulin treatment meant that a serious stage of the disease had been reached (before insulin, 36; after insulin 18 patients). It is concluded that such patients should, as part of group therapy, become active participants in the instructions given to diabetics so that other patients can profit from their experience.

Several studies have indicated that the long-term effectiveness of sulfonylurea therapy in the treatment of type-II diabetics is due to a potentiation of insulin action. The present investigation was undertaken in order to elucidate whether or not there is also an acute effect of sulfonylureas on insulin-mediated glucose uptake. Nine non-obese subjects classified as having impaired glucose tolerance formed the study group. In vivo insulin sensitivity was assessed by using the glucose controlled insulin infusion system (Biostator) without or with a contemporary 3-hour tolbutamide infusion. Studies were performed on subsequent days, and each subject served as its own control. Glucose was given at a fixed rate of 0.011 mmol/kg b.w./min. The computer program was set to maintain plasma glucose concentration at 3.89 mmol/l. The amount of exogenous insulin necessary to keep glycemia at this steady-state level has been accepted as an estimate of insulin sensitivity. Mean plasma glucose and insulin concentrations were constant and comparable in control and sulfonylurea treated groups. Under our experimental conditions tolbutamide did not provoke any increase of C-peptide secretion. There was no significant alteration of insulin counterregulatory hormones (glucagon and growth hormone) either. On the other hand, for the disposal of identical quantities of glucose the necessary amount of insulin has been found to be reduced by one third due to tolbutamide treatment indicating a higher insulin sensitivity. The mechanism by which tolbutamide intensifies the insulin effect is unknown. It seems to be that a successful short-term sulfonylurea therapy on glucose utilization is associated with some alterations on the receptor and/or post-receptor level.