Glucose profiles in children two years after the onset of type 1 diabetes

Sweet dreams?--nocturnal hypoglycemia in children with type 1 diabetes

Hypoglycemia is an inevitable consequence of the treatment of type 1 diabetes in childhood. Nocturnal hypoglycemia is often considered as merely the submerged part of this serious complication yet there are reasons to believe that hypoglycemia occurring during sleep may be different in physiological terms. Glucose homeostasis during fasting, delayed effects of exercise and alterations in sleep physiology, itself, may not only affect the risk of nocturnal hypoglycemia but may influence the ability to correct glucose concentration as it falls, leading to episodes of hypoglycemia which are both profound and prolonged. The etiology and potential repercussions are incompletely understood and the most appropriate defense remains unclear. A greater understanding of this enigmatic phenomenon is essential before appropriate methods for hypoglycemia avoidance can be developed.

Impact of improved glycaemic control on rates of hypoglycaemia in insulin dependent diabetes mellitus

Increased emphasis on strict glycaemic control of insulin dependent diabetes mellitus (IDDM) in young patients may be expected to cause increases in rates of significant hypoglycaemia. To evaluate whether this is the case for a large population based sample of IDDM children and adolescents rates of severe (coma, convulsion) and moderate (requiring assistance for treatment) hypoglycaemia were studied prospectively over a four year period. A total of 709 patients were studied yielding 2027 patient years of data (mean (SD) age: 12.3 (4.4); range 0-18 years, duration IDDM: 4.9 (3.8) years). Details of hypoglycaemia were recorded at clinic visits every three months when glycated haemoglobin (HbA1c) was also measured. Overall the incidence of severe hypoglycaemia was 7.8 and moderate was 15.4 episodes/100 patient years. Over the four years mean (SD) clinic HbA1c steadily fell from 10.2 (1.6)% in 1992 to 8.8 (1.5)% in 1995. In parallel with this there was a dramatic increase in the rate of hypoglycaemia, especially in the fourth year of the study, when severe hypoglycaemia increased from 4.8 to 15.6 episodes/100 patient years. This increase was particularly marked in younger children (< 6 years) in whom severe hypoglycaemia increased from 14.9 to 42.1 episodes/100 patient years in 1995. It is concluded that attempts to achieve improved metabolic control must be accompanied by efforts to minimise the effects of significant hypoglycaemia, particularly in the younger age group.

Incidence and predictive criteria of nocturnal hypoglycemia in young children with insulin-dependent diabetes mellitus

OBJECTIVE

To determine the incidence of significant nocturnal hypoglycemia occurring at home in young children with insulin-dependent diabetes mellitus using conventional therapy.

DESIGN

Sixty-one children (aged 2.6 to 8.5 years) were studied on one night, at home, with blood collection occurring at dinner, bedtime/supper, 11 PM, 2 AM, and breakfast, with subsequent laboratory analysis.

RESULTS

The proportion of subjects with blood glucose levels less than 64, 55, 45, and 36 mg/dl (3.5, 3.0, 2.5, and 2.0 mmol/L) was 37.8%, 17%, 13%, and 8%, respectively. Nocturnal hypoglycemia was associated with younger age (< 5 years 57% vs 5 to 8.5 years 36%; p < 0.001) and lowered glycosylated hemoglobin levels (HbA1c) with a greater than 50% incidence of hypoglycemia seen in subjects with HbA1c levels of less than 8.5%. The average HbA1c concentration was lower in the hypoglycemic group than in the nonhypoglycemic group (7.8 vs 8.3%; p < 0.02). Nocturnal hypoglycemia occurred with increasing frequency throughout the night in subjects less than 5 years of age (dinner, supper, 11 PM, 2 AM, and breakfast incidences being 0%, 12.5%, 26%, 33%, and 30%, respectively) but not in those older than 5 years. Carbohydrate intake at supper did not prevent subsequent hypoglycemia. Blood glucose levels at 11 PM were poor predictors of subsequent hypoglycemia at 2 AM in either the group as a whole or in the children less than 5 years of age. Symptom recognition of nocturnal hypoglycemia was decreased in younger children (< 5 years (36%) > 5 years (58%)), in those with a lower HbA1c, and when hypoglycemia occurred at breakfast rather than at dinner (0% vs 50%).

CONCLUSIONS

The incidence of nocturnal hypoglycemia in young children with insulin-dependent diabetes mellitus receiving conventional therapy is unacceptably high and is increased with lowered age and HbA1c concentration; the condition is often asymptomatic. Early-morning hypoglycemia is poorly predicted by a blood glucose determination at 11 PM and is not prevented by carbohydrate intake at supper. In younger children, blood glucose profiles should include early-morning measurements.

Serum insulin profiles in consecutive children 2 years after the diagnosis of IDDM

We studied associations of 24-h serum insulin profiles with insulin dose, age, gender, haemoglobin A1c (HbA1c) and C-peptide values, as well as blood glucose profiles in 77 consecutive children-nine aged 2-4, 14 aged 5-8, 26 aged 9-12, and 28 aged 13-17 years--2 years after the onset of insulin-dependent diabetes mellitus (IDDM). Mean weight-based insulin doses in the four age groups were similar (0.7 +/- 0.2 U.kg-1.day-1 in all); body surface-area-based doses differed. Insulin doses correlated significantly with the 24-h mean and area-under-the-curve (AUC) values, and with mean values at 03.00 hours of serum insulin in the children aged 5-8 and 13-17 years. The mean insulin concentrations of the age groups (95% confidence intervals) increased with age [6.1 (3.8, 9.7), 7.6 (5.9, 9.8), 10.4 (8.6, 12.4), and 14.0 (11.6, 16.8) mU/l; p < 0.0002]. The 24-h mean of serum insulin together with HbA1c concentration predicted 32% of the variation of mean blood glucose concentrations. Of children aged less than 9 years, 50% had insulin values less than 5 mU/l (healthy subjects' lower reference limit), and 14% were of less than 2 mU/l (detection limit of the assay) at 03.00 hours. At 07.00 hours, 82% had insulin values of less than 5 mU/l, and 36% were of less than 2 mU/l, respectively. Some young children had night-time hypoglycaemia with simultaneous hypoinsulinaemia. Insulin profiles correlated poorly with the HbA1c and peak C-peptide values.(ABSTRACT TRUNCATED AT 250 WORDS)