The relationship between glycosylated hemoglobin, time-in-range and glycemic variability in type 1 diabetes patients under flash glucose monitoring

OBJECTIVES

Flash glucose monitoring in patients with type 1 diabetes provides new glucometric data that allow for the assessment of glycemic control beyond HbA_1c. The objective of the study was to evaluate the relationship between HbA_1c, time-in-range (TIR) and glycemic variability in a cohort of paediatric and adult patients with type 1 diabetes and treatment with flash glucose monitoring.

MATERIAL AND METHODS

This was a cross-sectional study in 195 patients with type 1 diabetes (42.6% females, 70 paediatric, 26.2% continuous subcutaneous insulin infusion, 28.7% coefficient of variation [CV]≤36%) in intensive treatment and flash glucose monitoring. Clinical, analytical and glucometric data were evaluated.

RESULTS

The relationship between the TIR and HbA_1c showed a strong negative linear correlation (R=-0.746; R²=0.557; P<.001), modified in those patients with CV≤36% (R=-0.852; R²=0.836) compared to CV>36% (R=-0.703; R²=0.551). A similar correlation was found when evaluating the TIR and the Glucose Management Indicator (R=-0.846; R²=0.715; P<.001); in patients with CV≤36% (R=-0.980; R²=0.960) versus CV>36% (R=-0.837; R²=0.701); P<.001. Both correlations remained stable in the paediatric population (R=-0.724; R²=0.525; P<.001) and adults (R=-0.706; R²=0.498; P<.001) and by type of treatment: multiple doses of insulin (R=-0.747; R²=0.558; P<.001) and continuous subcutaneous insulin infusion (R=-0.711; R²=0.506; P<.001). In a multiple regression analysis evaluating HbA_1c as dependent variable, the only parameters that maintained statistical significance were the TIR (β=-0,031; P<.001), CV (β=0.843; P<.05) and TIR-CV interaction (β=-0.017; P<.01).

CONCLUSIONS

The glycemic variability defined by the CV modifies the relationship between the TIR and HbA_1c/Glucose Management Indicator and should be taken into account when individualising TIR targets, regardless of age or the type of treatment used.

Prevalence of insulin resistance and impaired glucose tolerance in a sample of obese Spanish children and adolescents

The prevalence of obesity in children has increased in developed countries in the last decades. It is associated with alterations in glucose metabolism that may be present in childhood. To assess the frequency of glucose metabolism alterations and insulin resistance and their possible determinants in a sample of obese children from Valladolid (Spain), we retrospectively studied 100 obese children and adolescents (11.59 ± 2.73 years). Anthropometric measures, biochemical parameters, and oral glucose tolerance test (OGTT) were performed. Insulin resistance was evaluated with fasting insulin, HOMA index, and insulin values in OGTT. Impaired glucose tolerance was found in 15% of the sample, and was the most frequent of glucose metabolism alterations. Impaired fasting glucose was found in 2%. No case of type 2 diabetes was found. Acanthosis nigricans was present in 22%, with predominance in females, but not all presented insulin resistance. The prevalence of insulin resistance was 29% when HOMA index was used, and 50% when the insulin response in OGTT was used. Not all patients with impaired glucose tolerance had a pathological HOMA index, and not all with pathological HOMA index presented insulin resistance when insulin values in OGTT were used. Higher 2-h post-OGTT insulin levels were found in children with impaired glucose tolerance. It is paramount to identify young people with glucose regulation alterations for early, intensive intervention to prevent or at least postpone the onset of type 2 diabetes. OGTT is a screening tool necessary to fulfill this objective.

Klinefelter syndrome and short stature: an unusual combination

Klinefelter syndrome is not easy to diagnose in childhood because of the absence of significant manifestations before puberty. Three main clinical signs should suggest the diagnosis in a child: small testes, tall stature, and mental retardation or learning problems. We present a patient with Klinefelter syndrome and short stature due to growth hormone deficiency. His height was below the third percentile for age and his bone age delayed. Maximal serum GH levels after insulin-induced hypoglycemia and clonidine were low, demonstrating GH deficiency. He received growth hormone treatment with good response. The diagnosis of Klinefelter syndrome was made at puberty, because the patient did not present a normal progression of testicular development and puberty. At that moment, a karyotype was made confirming the suspected diagnosis. We wish to emphasize the rare association between Klinefelter syndrome and growth hormone deficiency.