Calcium-phosphate homeostasis and insulin resistance in men

BACKGROUND AND AIMS

Data on P homeostasis in insulin resistance (IR) are still conflicting. We investigated calcium-phosphate homeostasis parameters in men with/without IR.

METHODS AND RESULTS

177 volunteers (aged 61.62 ± 12.11), whose body mass index (BMI) was 29.97 ± 6.35, were studied. On fasting blood and spot urine samples, we measured serum creatinine, sodium (sNa), potassium (sK), chloride (sCl), calcium (sCa), phosphate (sP), alkaline phosphatase total activity (ALP), glucose, insulin, parathyroid hormone (PTH), 25-hydroxy-vitamin D [25(OH)D], and urinary electrolytes corrected for creatinine (uNa/Cr, uK/Cr, uCl/Cr, uCa/Cr, and uP/Cr). Through the QUICKI index, we separated subjects with (IR+, n = 68) or without (IR-, n = 109) IR, and their parameters were compared. Associations were assessed by age-adjusted partial correlation, whose coefficients were compared by Fisher's transform. IR + had higher sP (3.54 ± 0.65 vs. 3.35 ± 0.47, p = 0.044) and lower uCa/Cr levels (0.073 ± 0.056 vs. 0.095 ± 0.072, p = 0.047) than IR-. BMI correlated with sP (r = 0.21, p < 0.05) and PTH (r = 0.29, p < 0.01). QUICKI negatively correlated with sCa (r = -0.22, p < 0.05) and positively with uCa/Cr (r = 0.21, p < 0.05), in turn correlating with uNa/Cr (r = 0.45, p < 0.001). In both groups, uCa/Cr correlated with eGFR and uNa/Cr (p < 0.05 to p < 0.001). In IR + only, sP correlated with BMI, PTH with insulin, and uP/Cr (p < 0.05 for all). IR+ and IR-coefficients differed (p < 0.05 to p < 0.001) for the correlation of sP with BMI and of PTH with insulin and uP/Cr.

CONCLUSION

The higher sP and lower uCa/Cr levels found in men with IR + suggest that IR could modulate calcium-phosphate homeostasis, likely by affecting their renal handling.

Can we Predict Incipient Diabetes Mellitus in Patients with Transfusion Dependent β-Thalassemia (β-TDT) Referred with a History of Prediabetes?

Background

Prediabetes and diabetes mellitus (DM) are complications in adult patients with transfusion-dependent β-thalassemia (β-TDT), with their incidence increasing with age.

Objective

This retrospective observational study describes the glycemic trajectories and evaluates predictive indices of β-cell function and insulin sensitivity/resistance in β-TDT patients with prediabetes, both in a steady state and during 3-h oral glucose tolerance test (OGTT), in order to identify patients at high risk for incipient diabetes.

Setting

The study was mainly conducted at the Pediatric and Adolescent Outpatient Clinic, Quisisana Hospital, Ferrara (Italy), in collaboration with thalassemia referring centers across Italy.

Patients

The study included 11 β-TDT (aged 15.11-31.10 years) with prediabetes. Methods: The ADA criteria for the diagnosis of glucose dysregulation were adopted. Investigations included evaluating plasma glucose levels and insulin secretion, analyzing glycemic trajectories and indices of β-cell function, and insulin sensitivity/resistance assessed in steady state and during OGTT.

Results

The duration of progression from prediabetes to DM, expressed in years, showed a positive direct correlation with corrected insulin response (CIR-30 = r: 0.7606, P: 0.0065), insulinogenic index (IGI 0-120 = r: 0.6121, P:0.045), oral disposition index (oDI = r: 0.7119, P:0.013), insulin growth factor-1 (IGF-1= r: 0.6246, P: 0.039) and an inverse linear correlation with serum ferritin (SF = r: -0.7197, P: 0.012). The number of patients with 1-hour post-load PG value ≥ 155 mg/dL ( ≥ 8.6 mmol/L) was at -4 years: 4/9 (44.4%); -3 years: 8/9 (88.8%); - 2 years: 7/10 (70 %) and at -1 year: 11/11 (100%) (PG range:162-217 mg/dL).

Conclusions

A progressive increase in 1-hour PG in response to OGTT is associated with progressive β-cell failure, peripheral resistance to insulin action, and reduced oDI and may be considered a relevant marker for incipient DM in β-TDT patients with prediabetes.

Incidence of diabetic retinopathy in newly diagnosed subjects with type 2 diabetes mellitus over 5 years: Contribution of Β-cell function

AIMS

Identifying and modulating risk factors is essential to prevent visual impairment due to diabetic retinopathy (DR). This study examines incident DR with metabolic and hormonal factors in newly-diagnosed, treatment naïve, individuals with Type2 Diabetes Mellitus (T2DM), over a 5 year period from diagnosis.

METHODS

233 T2DM subjects underwent serial DR screening using digital photography and standardised Meal Tolerance Tests at diagnosis and after 1, 2 and 5 years. Subjects (179) with no DR throughout the 5-year study period were compared with those who developed DR (54).

RESULTS

Of 233 subjects, 54(23.2%) developed DR by 5 years, background DR in 50(93%) and exudative maculopathy in 4(7%) individuals. Of these subjects, 12(22%) developed DR after 1 year, 15(28%) after 2 years and 27(50%) after 5 years. At baseline, those with DR at 5 years had higher HbA_1c (p = 0.017), higher fasting plasma glucose (PG) (p = 0.031) and postprandial PG (p = 0.009). They were associated with reduced basal β-cell secretory function (M₀) (p = 0.025), lower (p = 0.000) postprandial β-cell responsiveness (M₁) and β-cell function (HOMA-B) (p = 0.044).

CONCLUSIONS

There is an independent association between glycaemic control and β-cell dysfunction at the time of diagnosis of T2DM, with incident DR over a follow-up period of 5 years.