ROCHESTER, N.Y. — A popular insulin pen is in short supply across the country, leaving people scrambling to find alternatives. The medication, Lantus Solostar, is a popular choice for adults and kids with diabetes. “We’ve been able to give most of our patients the quantities that they’ve been prescribed. But we haven’t been able to really take on new patients with new Lantus prescriptions,” said Jessica Cavallaro, a pharmacist. The manufacturer says the situation is temporary and expects supplies to improve over the coming weeks.