INS and vitamin D deficiency: The non-GDM and GDM groups differed significantly with respect to serum vitamin D deficiency: 249 (82.5%) and 108 (93.1%), (p = 0.006); glucose (in mmol/l): [4.7 (4.3–5.2)], [5.1 (4.6–5.6)], (p < 0.01); age (years): (28.6 ± 5.1), (30.3 ± 5.6), (p = 0.03); HbA1c: (5 ± 0.4), (5.2 ± 0.5) (p < 0.01); triglycerides (mmol/l): (1.3 ± 0.6), (1.5 ± 0.6), (p = 0.018) and insulin (in uU/ml) [8.7 (4.4–19.5)], [11.5 (6.2–19.8)], (p = 0.048).