Glycemic Variability and Insulin Needs in Patients with Type 1 Diabetes Mellitus Supplemented with Vitamin D: A Pilot Study Using Continuous Glucose Monitoring System

BACKGROUND

Recent studies suggest that glycemic variability could influence the risk of complications in Type 1 Diabetes Mellitus (T1DM). There are no data about the action of Vitamin D (VD) on glycemic variability. Our pilot study aims to evaluate glycemic variability and insulin needs in patients with T1DM supplemented with VD.

METHODS

22 Patients received doses of 4000 and 10000 IU/day of cholecalciferol for 12 weeks, according to the patient's baseline VD levels and underwent continuous glucose monitoring system.

RESULTS

Correlations were found between percentage variation (Δ) of glycemia standard deviation (ΔSDG), calculated using continuous glucose monitoring, with Δ of basal (r = 0.6; p <0.01) and total insulin dose (r = 0.6; p <0.01). Correlations between VD status after supplementation and Δ of prandial (r = 0.5; p <0.05) and total insulin dose (r = 0.4; p <0.05) were found, suggesting that the dose of insulin needed by patients is lower when VD status is better. We divided patients in two subgroups: SDG improved (subgroup 1; N = 12 (55%)) and SDG worsened (subgroup 2; N = 10 (45%)). Group 1, compared to subgroup 2, required a lower insulin dose (Δbasal insulin dose = -8.0 vs. 6.3%; p <0.05) and had a lower frequency of hypoglycemia (27% vs. 64%, hypoglycemias/days evaluated; p <0.01).

CONCLUSION

Our study suggests a relation between VD supplementation, improved glycemic variability, lower insulin needs and lower frequency of hypoglycemia in patients with T1DM.

Vitamin D and PTH: data from a cross-sectional study in an equatorial population

OBJECTIVE

Investigate the prevalence of vitamin D deficiency in an equatorial population through a large-sample study.

METHODS

Cross-sectional study with 30,224 healthy individuals from the North Region, in Brazil (Amazônia - state of Pará), who had 25-hydroxy-vitamin D (25(OH)D) and intact parathyroid hormone (PTH) serum levels measured by immunoassay method. Those with history of acute or chronic diseases were excluded. Abnormal levels of calcium, creatinine, glycemia and albumin were also exclusion criteria.

RESULTS

25(OH)D levels were 29.1 ± 8.2 ng/mL and values <12.7 ng/mL were equal to < -2 s.d. below average. Hypovitaminosis D was present in 10% of subjects according to the Institute of Medicine (values <20 ng/mL) and in 59%, in consonance with Endocrine Society (values 20-30 ng/mL as insufficiency and <20 ng/mL as deficiency) criteria. Individuals were divided according to four age brackets: children, adolescents, adults and elderly, and their 25(OH)D levels were: 33 ± 9; 28.5 ± 7.4; 28.3 ± 7.7; 29.3 ± 8.5 ng/mL, respectively. All groups differed in 25(OH)D, except adolescents vs adults. Regression model showed BMI, sex, living zone (urban or rural) and age as independent variables to 25(OH)D levels. Comparing subjects with vitamin D deficiency (<20 ng/mL) to those with vitamin D insufficiency (20-30 ng/mL), a difference between PTH levels in these two groups was observed (95.9 ± 24.7 pg/mL vs 44.2 ± 64.5 pg/mL; P < 0.01). Additionally, the most accurate predictive vitamin D level for subclinical hyperparathyroidism in ROC curve was 26 ng/mL.

CONCLUSION

Our equatorial population showed low prevalence of vitamin D hypovitaminosis ranging with age bracket. The insufficient category by Endocrine Society was corroborated by our PTH data.

High-dose Vitamin D Supplementation on Type 1 Diabetes Mellitus Patients: Is there an Improvement in Glycemic Control?

BACKGROUND

Some authors evaluated the effect of VD on hyperglycemia in T1DM, but the results remain controversial. This study aims to analyze the effects of high-dose VD supplementation on T1DM patients' glycemic levels, maintaining stable doses of insulin.

METHODS

Prospective, 12-week clinical trial including 67 T1DM patients, supplemented with high doses of cholecalciferol according to participants' VD value. Patients with VD levels below 30 ng/mL received 10,000 IU/day; those with levels between 30-60 ng/mL received 4,000 IU/day. Patients who had not achieved 25(OH)D levels > 30 ng/ml or presented insulin dose variation during the study were not analyzed.

RESULTS

Only 46 out of 67 patients accomplished the criteria at the end of the study. There was no general improvement in the glycemic control evaluated by HbA1c (9.4 ± 2.4 vs 9.4 ± 2.6, p=NS) after VD supplementation. However, a post-hoc analysis, based on HbA1c variation, identified patients who had HbA1c reduced at least 0.6% (group 1, N = 13 (28%)). In addition, a correlation between 25(OH)D levels with HbA1c and total insulin dose at the end of the study was observed (r = -0.3, p<0.05; r=-0.4, p<0.05, respectively), and a regression model demonstrated that 25(OH)D was independent of BMI, duration of T1DM and final total insulin dose, being capable of determining 9.2% of HbA1c final levels (Unstandardized B coefficient = -0.033 (CI 95%: -0.064 to -0.002), r2 = 0.1, p <0.05).

CONCLUSION

Our data suggest that VD is not widely recommended for glycemic control. Nevertheless, specific patients might benefit from this approach.

Peripheral arterial disease progression and ankle brachial index: a cohort study with newly diagnosed patients with type 2 diabetes

BACKGROUND

Little is known about the evolution of peripheral arterial disease (PAD) since diagnosis and its association with glycemic and lipid control in patients with Type 2 Diabetes Mellitus (T2DM).

OBJECTIVE

Evaluate the actual criteria to start screening PAD with ankle-brachial index (ABI) in T2DM patients and assess its progression and relationship with glycemic and lipid control since diagnosis.

METHODS

We performed a 3-year prospective cohort study with two groups: group 1 (978 individuals with T2DM undergoing drug treatment) and group 2 [221 newly diagnosed drug-naive (< 3 months) patients with T2DM]. PAD diagnosis was by ABI ≤ 0.90, regardless any symptoms.

RESULTS

As expected, abnormal ABI prevalence was higher in group 1 vs. Group 2 (87% vs. 60%, p < 0.001). However, abnormal ABI prevalence did not differ between patients over and under 50 years in both groups. Our drug-naive group stabilizes ABI (0.9 ± 0.1 vs 0.9 ± 0.1, p = NS) and improved glycemic and lipid control during follow-up [glycated hemoglobin (HbA1c) = 8.9 ± 2.1 vs 8.4 ± 2.3%, p < 0.05; LDL = 132 ± 45 vs 113 ± 38 mg/dL, p < 0.01, respectively]. When compared, patients who evolved with normalization or maintained normal ABI levels at the end [Group A, N = 60 (42%)] with those who decreased ABI to abnormal levels (ABI basal 1.0 ± 0.1 vs final 0.85 ± 0.1, p < 0.001) [Group B, N = 26 (18%)], an improvement in HbA1c (9 ± 2 vs 8 ± 2%, p < 0.05) and a correlation between the final HbA1c with ABI (r = - 0.3, p = 0.01) was found only in the first. In addition, a correlation was found between albuminuria variation and ABI solely in group A (r = - 0.3; p < 0.05).

CONCLUSION

Our study suggests that ABI should be measured at diagnosis in T2DM patients, indicating that current criteria to select patients to screen PAD with ABI must be simplified. An improvement in albuminuria and glycemic and lipid control could be related with ABI normalization in newly diagnosed T2DM drug-naive patients.

Heart rate variability tests for diagnosing cardiovascular autonomic neuropathy in patients with type 2 diabetes mellitus in advanced stages of kidney disease

Cardiovascular Autonomic Neuropathy (CAN) is one of the most devastating complications of Diabetes Mellitus (DM) and presents high morbidity and mortality. Its association with diabetic kidney disease (DKD) worsens the condition even further. CAN diagnosis remains a challenge and is being based on reflex tests which are laborious, risky and difficult to perform. Heart Rate Variability (HRV) tests has been suggested as having high utility in diagnosing CAN, but this issue remains controversial. The aim is to evaluate the sensitivity and specificity of HRV tests to diagnose CAN in patients with type 2 diabetes mellitus (T2DM) and DKD with severely increased albuminuria. This is a cross-sectional study in patients with T2DM and DKD with severely increased albuminuria. A total of 48 subjects were recruited and underwent laboratory and neuropathy assessment. The diagnosis of CAN was first confirmed in 75% (36/48) of patients based on cardiovascular autonomic reflex tests (CARTs). HRV tests (VLF, LF, TP and SDNN) differed between groups with and without CAN (212 vs. 522 ms2, p = 0.024; 57 vs. 332 ms2, p = 0.025; 359.5 vs. 2733 ms2, p = 0.007; 20 vs. 48 ms, p = 0.012), respectively. The best cut-off points based on ROC curve were < 1,117 ms2, < 152.5 ms2, < 1,891 ms2 and < 46.5 ms, respectively. VLF and TP reached highest sensitivity values (97% and 92%) and F1 Score of 90%, while LF had best specificity (75%) and TP had best accuracy (85%). Our best model of serial algorithm using VLF as first screening test and TP in sequency obtained a sensitivity of 97% and accuracy of 90%, reducing in 90% the need to perform CARTs. Our findings suggest that it is possible to achieve high sensitivity and accuracy using an algorithm with VLF and TP parameters analyzed in series. It could enable a simpler and early diagnosis, avoiding CARTs complications.