A 28-year-old G1P0 woman at 26 weeks' gestation presents to the antenatal clinic for a follow-up visit. She reports feeling well overall, though she has noticed increased thirst in recent weeks. Her initial routine 1-hour 50 g oral glucose tolerance test, performed at 24 weeks' gestation, yielded an elevated plasma glucose level. She denies any prior history of diabetes or other chronic medical conditions. Given these findings, what is the most appropriate next diagnostic step and the immediate nutritional counseling that should be initiated?

A 32-year-old G1P1001 woman presents to her postpartum clinic for a routine 6-week check-up. She had a scheduled induction of labor at 39 weeks due to poorly controlled gestational diabetes. Despite initial diet and lifestyle management, her glycemic control remained suboptimal, with postprandial glucose levels consistently in the 9.4-10.0 mmol/L (170-180 mg/dL) range, necessitating insulin therapy throughout the latter half of her pregnancy. Her family history includes diabetes in her mother and grandmother. She achieved an appropriate weight gain during pregnancy, with a pre-pregnancy BMI of 22.4 kg/m^2. Her last ultrasound 1 month prior to delivery estimated fetal weight at 4100 g, with an updated measurement of 4560 g on arrival at the labor floor. Delivery was complicated by shoulder dystocia, which resolved after 3 minutes with internal rotation. Her newborn male infant, now 6 weeks old, demonstrates an absent Moro reflex on the left side and frequently assumes a characteristic posture of adduction, internal rotation, and extension of the left arm, as previously observed in the immediate postnatal period. The mother's current blood pressure is 115/70 mmHg, pulse 78/min, and respirations 14/min. The infant's growth and development have otherwise been satisfactory. What is the most likely diagnosis for this infant's condition, and what is the most appropriate next step in the mother's long-term metabolic assessment?

A 28-year-old G1P1001 female delivered a full-term male infant via spontaneous vaginal delivery, following an uncomplicated labor. Her prenatal course was notable for newly diagnosed gestational diabetes managed with dietary modifications and insulin, with inconsistent adherence to glucose monitoring, resulting in fluctuating blood glucose levels throughout her pregnancy. The infant, weighing 4.3 kg (9 lbs 8 oz) at birth, had Apgar scores of 8 and 9 at 1 and 5 minutes, respectively. Two hours postpartum, while in the newborn nursery, the nurse observes the infant to be irritable, with episodes of tremors. Physical examination reveals an infant who is lethargic, hypotonic, and exhibits a weak suck reflex. His temperature is 36.0°C, heart rate is 105 beats/min, respiratory rate is 58 breaths/min, and blood pressure is 75/45 mmHg. The infant then experiences a brief episode of generalized tonic-clonic movements, which resolves spontaneously. What is the most likely underlying condition and the immediate therapeutic intervention required?