Ensure insulin effects cover glucose values for ICE calc when running forecast previews

Author: ps2

Loop/Managers/LoopDataManager.swift

@@ -1365,14 +1365,15 @@ extension LoopDataManager {
         let retrospectiveStart = glucose.date.addingTimeInterval(-type(of: retrospectiveCorrection).retrospectionInterval)
         let earliestEffectDate = Date(timeInterval: .hours(-24), since: now())
         let nextEffectDate = insulinCounteractionEffects.last?.endDate ?? earliestEffectDate
+        let insulinEffectStartDate = nextEffectDate.addingTimeInterval(.minutes(-5))
 
         let updateGroup = DispatchGroup()
         let effectCalculationError = Locked<Error?>(nil)
 
         var insulinEffect: [GlucoseEffect]?
         let basalDosingEnd = includingPendingInsulin ? nil : now()
         updateGroup.enter()
-        doseStore.getGlucoseEffects(start: nextEffectDate, end: nil, basalDosingEnd: basalDosingEnd) { result in
+        doseStore.getGlucoseEffects(start: insulinEffectStartDate, end: nil, basalDosingEnd: basalDosingEnd) { result in
             switch result {
             case .failure(let error):
                 effectCalculationError.mutate { $0 = error }