Endocrine Abstracts

Introduction: Low vitamin D status has been associated to COVID-19 risk, and type 2 diabetic patients are a vulnerable group. Even though the Canarian archipelago is one of the sunniest spots in Europe, our prevalence of vitamin D deficit is known to be very high. The mandatory lockdown may have worsened this deficit, increasing the need for vitamin D supplementation.

Objectives: Our main objective was to assess and compare the prevalence of vitamin D deficit in supplemented and unsupplemented type 2 diabetic patients from Northern Gran Canaria during the 12 week lockdown started on March 15th 2020. A secondary aim was to correlate the strike rate of COVID-19 with the calcifediol status of the patients.

Methods: Plasma calcifediol levels were sampled in an unselected type 2 diabetic population, along with age, gender, vitamin D supplementation status and confirmed COVID-19 status.

Results: Data were obtained from 239 consecutive patients, 140 female (58.6%), mean age 57.9 ± 16.7. 97 (40.6%) were taking vitamin D supplements years. Mean plasma calcifediol was 30.1 ± 13.2 ng/ml; but it was lower than recommended (<30 ng/ml), in 57.3% of the patients, deficient (<20 ng/ml) in 22.2% and severely deficient (<12 ng/ml) in 5.0%. In supplemented patients, calcifediol was mostly adequate (mean 41.0 ± 12.4 ng/ml, with 22.7% < 30 ng/ml, 4.1% < 20 ng/ml, none < 12 ng/ml and none > 80 ng/ml) but low in unsupplemented patients (mean 22.7 + 7.3 ng/ml, with 81.0% < 30 ng/ml, 34.5% < 20 ng/ml and 8.5% < 12 ng/ml). Plasma calcifediol was significantly higher in supplemented patients (unpaired t-test, P < 0.0001) and the proportions of low, deficient and severely deficient patients were significantly lower (Fisher’s exact test, P < 0.0001, P < 0.0001 and P = 0.0062, respectively). The strike rate of COVID-19 was fortunately very low in this population (1.26%) with 3 confirmed cases (all of them mild, 2 in unsupplemented and 1 in supplemented patients), and though numerically lower in supplemented patients (1.03% vs. 1.41%) it could not be meaningfully analyzed.

Conclusions: With a mandatory lockdown right after the winter months, the prevalence of low calcifediol levels in our unsupplemented type 2 diabetic population is extremely high. On the other hand, when taking vitamin D supplements their vitamin D status is satisfactory with < 5% deficient patients and none severely deficient. We cannot conclude that vitamin D supplements were associated with protection from COVID-19; however, their use was effective to prevent the deprivation associated with lockdown.