Association between glycaemic outcome and BMI in Danish children with type 1 diabetes in 2000-2018: a nationwide population-based study

AIM

To describe the development of HbA_1c and BMI over time in Danish children with type 1 diabetes; and to investigate the association between HbA_1c and BMI including influence of age, gender, diabetes duration, severe hypoglycaemia and treatment method.

METHODS

We used the nationwide Danish Registry of Childhood and Adolescent Diabetes, DanDiabKids, including annual registrations of all children with diabetes treated at Danish hospitals. With linear mixed-effects models and splines we analyzed the HbA_1c and BMI development over time as well as the association between HbA_1c and BMI including effects of gender, age, disease duration, hypoglycaemia and treatment method. BMI z-scores were calculated for these analyses.

RESULTS

For the period from 2000 to 2018, 6097 children with type 1 diabetes were identified from the DanDiabKids database. The median (interquartile range) HbA_1c level was 65 (57-74) mmol/mol (8.1%) and the median BMI z-score was 0.85 in girls and 0.67 in boys. A non-linear association was found between HbA_1c and BMI z-score, with the highest BMI z-score observed for HbA_1c values in the range of approximately 60-70 mmol/mol (7.6-6.8%). The association was modified by gender, age and diabetes duration. Severe hypoglycaemia and insulin pump treatment had a small positive impact on BMI z-score.

CONCLUSION

The association between HbA_1c and BMI z-score was non-linear, with the highest BMI z-score being observed for intermediate HbA_1c levels; however, specific patterns depended on gender, age and diabetes duration.

Nationwide reduction in the frequency of severe hypoglycemia by half

AIMS

To examine contemporary rates of severe hypoglycemia (SH) and identify the effect of predictors of SH in a pediatric type 1 diabetes population.

METHODS

The national diabetes register provided data on children residing in Denmark from 2008 to 2013 in this register-based population study. Robust Poisson regression models were applied.

RESULTS

The study population [n = 2,715 (50.9 % boys), mean (SD) age at onset; 8.1 (4.0) years, diabetes duration; 5.6 (4.9) years] comprised 7,390 person-years of data and 561 events of SH. The overall incidence of SH was 7.6 per 100 person-years. The incidence rate peaked with 16.0 per 100 person-years in 2008 reaching a nadir of 4.9 in 2011. Overall, insulin pump reduced the rate of SH with 27 % compared to any pen treatment (P = 0.003). When stratifying pen treatment, premixed insulin increased the rate of SH by 1.9-fold (P = 0.0015) and NPH increased the rate by 1.6-fold (P = 0.003) versus pump treatment, whereas long-acting insulin analogues were comparable with pump treatment (P = 0.1485). We found no association of SH with glycemic control (P > 0.05).

CONCLUSIONS

A nationwide halving in rates of severe hypoglycemia was observed during the study period independent of the prevailing average HbA1c level. Changes in diabetes care and successful educational programs may have influenced the lower incidence rate of severe hypoglycemia.

Hypophosphatemic rickets with hypercalciuria due to mutation in SLC34A3/NaPi-IIc can be masked by vitamin D deficiency and can be associated with renal calcifications

Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is caused by mutations in SLC34A3, the gene encoding the renal sodium-phosphate co-transporter NaPi-IIc. Despite increased urinary calcium excretion, HHRH is typically not associated with kidney stones prior to treatment. However, here we describe two sisters, who displayed nephrolithiasis or nephrocalcinosis upon presentation. The index patient, II-4, presented with short stature, bone pain, and knee X-rays suggestive of mild rickets at age 8.5 years. Laboratory evaluation showed hypophosphatemia, elevated 1,25(OH) (2) vitamin D levels, and hypercalciuria, later also developing vitamin D deficiency. Her sister, II-6, had a low normal serum phosphorous level, biochemically vitamin D deficiency and no evidence for osteomalacia, but had undergone left nephro-ureterectomy at age 17 because of ureteral stricture secondary to renal calculi. Nucleotide sequence analysis of DNA from II-4 and II-6 revealed a homozygous missense mutation c.586G>A (p.G196R) in SLC34A3/NaPi-IIc. Ultrasonographic examinations prior to treatment showed grade I nephrocalcinosis for II-4, while II-6 had grade I-II nephrocalcinosis in her remaining kidney. Four siblings and the mother were heterozygous carriers of the mutation, but showed no biochemical abnormalities. With oral phosphate supplements, hypophosphatemia and hypercalciuria improved in both homozygous individuals. Renal calcifications that are presumably due to increased urinary calcium excretion can be the presenting finding in homozygous carriers of G196R in SLC34A3/NaPi-IIc, and some or all laboratory features of HHRH may be masked by vitamin D deficiency.

Significance of mutations in the androgen receptor gene in males with idiopathic infertility

Abnormal human spermatogenesis is caused by a variety of genetic and acquired conditions. Because spermatogenesis is dependent on androgens, some males may have a minimal form of androgen insensitivity that does not inhibit virilization but impairs fertility. This has lead us to investigate the possibility of abnormalities in the androgen receptor (AR) gene in a large cohort of males suffering from infertility of unknown cause. We studied 180 males with variable impairment of spermatogenesis. In all patients, serum levels of testosterone and gonadotropins were analyzed to define an androgen sensitivity index (ASI). Single-strand conformation analysis and direct DNA sequencing of PCR-amplified blood leukocyte DNA were used to identify mutations within the whole coding region of the AR-gene. Endocrine and molecular investigations were compared with 53 normal males with proven fertility. In three infertile males, mutations in the AR were identified. Two unrelated males had the same variation within the first exon encoding for the transactivation domain of the receptor (Pro390Ser), whereas, in the third, a mutation in the hormone-binding region was characterized (Gln798Glu). All identified mutation carriers had a significantly elevated ASI. A proportion of males with idiopathic infertility carry relevant variations within the AR-gene. These males may be distinguished on the basis of hormone levels, calculating the ASI, although this index lacks specificity.